Analysis and interpretation of our results
It has been estimated that in 2006 about 1,350,000 articles were published in peer-reviewed journals (Björk et al 2008). The data suggest that the coverage in SCI is lower than in other databases and decreasing over time. It is also indicated that the coverage in SCI/SCIE is lower in high growth disciplines and in Conference Contributions than in well established fields like chemistry and physics. These indications are supported by complementary evidence from the literature. However, it must be remarked that SCI never has aimed at complete coverage, see below. The coverage of SCIE and SSCI has increased substantially in 2009, both by inclusion of more regional journals (Testa 2008a) and by general expansion/Thomson Reuters 2009b). The problems about the coverage of SCI/SCIE will be discussed again in “Fast- and slow-growing disciplines” and in the “Conclusion”.
The growth rate for SSCI is remarkably small. It is desirable to obtain supplementary information about the volume and growth rate of the publication activity in social sciences.
The growth rate of scientific publication and the growth rate of science
It is a common assumption that publications are the output of research. This is a simplistic understanding of the role of publication in science. Publication can just as well be seen as a (vital) part of the research process itself. Publications and citations constitute the scientific discourse (Ziman 1968; Mabe and Amin 2002; Crespi and Geuna 2008; Larsen et al. 2008). Nevertheless, the numbers of scientific publications and the growth rate for scientific publication generally are considered important science productivity or output indicators. The major producers of science indicators, the European Commission (EC), National Science Board/National Science Foundation (NSB/NSF, USA) and OECD all report publication numbers as output indicators (European Commission 2007; National Science Board 2008; OECD 2008). All base their data on SCI/SCIE, as do in fact virtually all others using publication number statistics. The data reported by NSB are nearly (but not completely) identical with those obtained directly from SCI/SCIE.
In 2008 NSB reported that the world S&E article output between 1995 and 2005 grew with an average annual rate of 2.3%, reaching 710,000 articles in 2005. This is based on the values for Articles + Letters + Notes + Reviews reported in SCI and in agreement with our results.
However, there are technical problems in counting publications (Gauffriau et al. 2007). In whole counting one credit is conferred to each country contributing to a publication. Whole counting involves a number of problems. Among these are that the numbers are non-additive, and therefore the publication number for a union of countries or for the world can be smaller than the sum of the publication numbers for the countries in the union or for the world. Indiscriminate use of whole counting leads to double counting. On the other hand, whole counting provides valuable information about the extent of scientific cooperation. In whole-normalized counting (fractional counting) 1 credit is divided equally between the countries contributing to a publication. Values obtained by whole-normalized counting are also non-additive. However, the values obtained by whole-normalized counting for large data sets are close to those obtained by complete-normalized counting (Gauffriau et al. 2008). In complete-normalized counting 1 credit is divided between the countries contributing to a publication in proportion to the number of institutions from each country contributing to the publication. Numbers obtained by complete-normalized counting are additive and can be used for calculating world shares. It is problematic that EC is using whole counting whereas NSB/NSF is using complete-normalized counting (National Science Board 2008). A publication by May (1997) with a high impact can serve as an example of the problems. A worldwide growth rate for scientific publication of 3.7% per year in the period 1981–1994 is reported. The real value, derived from SCI, is 2.3% per year. The incorrect figure must be due to the use of whole counting values and addition of non-additive numbers. The problems due to the use of different counting methods are also disclosed in comparisons of publication output between EU and USA. The use of whole counting shows a fast growth rate for EU-27 from 1981 to 2004 and a significant growth rate for USA from 1981 to 1995 but subsequently nearly no growth. Complete-normalized counting shows that the growth, both for EU and for USA, stopped completely in the period from 2000 to 2004 (Larsen et al. 2008). The counting problems are caused by scientific cooperation. If there was no scientific cooperation there would be no counting problems.
Mabe and Amin (2002) have given a precise description of the increasing extent of scientific cooperation. The authors write about the information explosion and to the rhetorical question “Is more being published?” give the answer “Based on papers published per annum recorded by ISI, the answer has to be an emphatic ‘yes!’”. However, using data from ISI they have for the period 1954–1998 calculated the number of papers per authorship, the average annual co-authorship, and the number of papers per unique author. The number of papers per authorship corresponds to whole counting. The number of papers per unique author is based on the total number of papers and the total number of active authors identified in the databases (the method used to solve the problem about homonyms is not stated). The number of authors per paper has increased from about 1.8 to about 3.7 in the period studied. Correspondingly, the number of papers per authorship has increased from about 1.8 to about 3.9. On the other hand, the number of papers per unique author has decreased from 1 to 0.8. Therefore the “productivity” of scientists has been decreasing slowly.
A possible explanation for this decrease in productivity is that in some disciplines a publication demands more and more work. Another possibility is that an increasing share of scientific publication consists of Conference Contributions not covered by the databases and publications presented for example on home pages or in open archives and again not covered by the databases. Anyway, Mabe and Amin conclude that “further analysis shows that the idea that scientists are slicing up their research into “least-publishable units” (or that “salami-style” publishing practices are occurring) appears to be unfounded.”
Mabe and Amin (2001) refer to National Science Foundation’s Science and Engineering Indicators 2000 reporting a 3.2% annual growth in research and development manpower for a selection of six countries over the period 1981 to 1995. They write that data for the rest of the world are hard to obtain, but that a figure of around 3–3.5% is not unlikely for the world as a whole. In continuation they note that article growth in ISI databases has also been estimated at 3.5% in the period from 1981 to 1995. This is however not in agreement with our analysis of SCI data where we find a growth rate of 2.0% for all source items and 2.2% for Articles + Letters + Notes + Reviews. This again indicates that the “productivity” of science is decreasing when measured as the ratio between the number of traditional scientific publications and the scientific manpower.
Crespi and Geuna (2008) have discussed the output of scientific research and developed a model for relating the input into science to the output of science. They are aware that science produces several research outputs, classified into three broadly defined categories: (1) new knowledge; (2) highly qualified human resources; and (3) new technologies and other forms of knowledge that can have a socioeconomic impact. Their study is focused on the determinants of the first type of research output. There are no direct measures of new knowledge, but previous studies have used a variety of proxies. As proxies for the output of science they use published papers and citations obtained from the Thomson Reuters National Science Indicators (2002) database. However, they are aware of the shortcomings in these two indicators (see below).
The number of scientific journals
As mentioned in the “Introduction”, Price wrote that by 1950 the number of journals in existence sometime between 1650 and 1950 was about 60,000 and with the known growth rate the number would be about 1 million in year 2000 (Price 1961). This seems unrealistic but in 2002 it was reported that 905,090 ISSN numbers had been assigned to periodicals (Centre International de l’ISSN 2008). How many of these are scientific periodicals, how many are in existence today, and are there periodicals not recorded in the international databases?
In 1981 it was reported that there were about 43,000 scientific periodicals in the British Library Lending Division (BLLD) and that BLLD attempted exhaustive coverage of the world’s scientific literature with a stated policy of subscribing to any scientific periodical requested if it had scientific merit (Carpenter and Narin 1982).
The question has been taken up by Mabe and Amin (2001). Based on Ulrich’s International Periodicals Directory on CD-ROM, they give a graphical representation of the numbers of unrefereed academic journals, refereed academic journals and active, refereed academic journals from 1900 to 1996. The number of unrefereed academic journals is about 165,000 in 1996. The numbers for refereed academic journals and active, refereed academic journals are about 11,000 and 10,500 in 1995. The growth rate for active, refereed journals is given as 3.31% per year for the period 1978–1996. In a subsequent publication (Mabe and Amin 2002) it is stated with reference to the first publication, that there are about 14,000 peer-reviewed learned journals listed in Ulrich’s Periodicals Database. No information is given about the year for which the value of 14,000 is valid. Even if it is the year of the publication 2002, 3.31% annual growth from 1995 to 2002 gives only 13,188 journals but no explanation is given for this discrepancy.
However, in a third publication (Mabe 2003) it is reported that the number of active, refereed academic/scholarly serials comes to 14,694 for 2001. This number is based on a search using Ulrich’s International Periodicals Directory on CD-ROM, Summer 2001 Edition. It is stated that this number is noticeably lower than estimates given by other workers but almost certainly represents a more realistic number. In this publication an annual growth rate of 3.25% is given for the period from 1970 to the present time.
Harnad et al. (2004) stated with reference to Ulrich that about 24,000 peer-reviewed research journals existed worldwide.
On the other hand van Dalen and Klamer (2005) reported that according to Ulrich’s International Serials Database in 2004 about 250,000 journals were being published, of which 21,000 were refereed. Again, Meho and Yang (2007) stated that approximately 22,500 active academic/scholarly, refereed journals were recorded in Ulrich’s Periodicals Directory.
According to Björk et al. (2008) the number of peer-reviewed journals was 23,750 in the winter of 2007. This figure was based on a search of Ulrich’s database.
Scopus (see “Citations and differences in citations recorded by different search systems”) in 2008 covers 15,800 peer-reviewed journals from more than 4,000 international publishers.
To conclude, the number of serious scientific journals today most likely is about 24,000. This number includes all fields, that is all aspects of Natural Science, Social Science and Arts and Humanities. There is no reason to believe that the number includes conference proceedings, yearbooks and similar publications. The number is of course important in considerations about the coverage of the various databases (see below in “Citations and differences in citations recorded by different search systems”). For comparison SCIE covered 6,650 journals and SSCI 1,950 journals in 2008 (Björk et al. 2008).
It must however be added that the criterion for regarding a journal as a serious scientific journal is peer review. Peer review in its modern present form is only about 40 years old and is not standardized. Therefore, the distinction between peer-reviewed journals and journals without peer review is not precise. It is worthwhile mentioning that a systematic peer review for Nature was only introduced in 1966 when John Maddox was appointed editor of this journal. Proceedings of the National Academy of Sciences introduced peer review only a few years ago.
Citations and differences in citations recorded by different search systems
Until a few years ago, when citation information was needed, the single most comprehensive source was the Web of Science including SCI and SSCI but recently two alternatives have become available.
Scopus was developed by Elsevier and launched in 2004 (Reed Elsevier 2008). In 2008 Scopus covers references in 15,800 peer-reviewed journals.
Google Scholar records all scientific publications made available on the net by publishers (Google 2008). A publication is recorded when the whole text is freely available but also if only a complete abstract is available. The data comes from other sources as well, for example freely available full text from preprint servers or personal websites.
A number of recent studies have compared the number of citations found and the overlap between the citations found using the three possibilities.
The use of Google Scholar as a citation source involves many problems (Meho 2006; Bar-Ilan 2008). But it has repeatedly been reported that more citations are found using Google Scholar than by using the two other sources and also that there is only a limited overlap between the citations found through Google Scholar and those found using the Web of Science (Meho 2006; Meho and Yang 2007; Bar-Ilan 2008; Kousha and Thelwall 2008; Vaughan and Shaw 2008, and references therein).
Meho and Yang (2007) have studied the citations found in 2006 for 1,457 scholarly works in the field of library science from the School of Library and Information Science at Indiana University-Bloomington and published in the period from 1970 to 2005. 2,023 citations of these publications in the period from 1996 to 2005 were found in the WoS, in Scopus 2,301 and in Google Scholar 4,181. There was a great deal of overlap between WoS and Scopus but Scopus missed about 20% of the citations caught in WoS whereas WoS missed about 30% of the citations caught in Scopus. There was restricted overlap between on the one side WoS and Scopus and on the other side Google Scholar. 60% of the citations caught in Google Scholar were missed by both WoS and Scopus whereas 40% of the citations caught in WoS and/or Scopus were missed by Google Scholar.
Kousha and Thelwall (2008) have reported a study involving the comparisons of citations in four different disciplines, biology, chemistry, physics and computers (In all fields only journals were included when giving open access and therefore accessible to Google Scholar as well as to WoS). The citations were collected in January 2006. From the data given in Table 1, page 280, it can be calculated that the ratios found for the four fields between citations found in Google Scholar and in WoS are 0.86, 0.42, 1.18 and 2.58. The citations common to WoS and Google Scholar represented 55, 30, 40 and 19% respectively of the total number of references. The dominant types of Google Scholar unique citing sources were journal papers (34.5%), conference/workshop papers (25.2%) and e-prints/preprints (22.8%). There were substantial disciplinary differences between types of citing documents in the four disciplines. In biology and chemistry 68, respectively 88.5% of the unique citations from Google Scholar were from journal papers. In contrast, in physics e-prints/preprints (47.7%) and in computer science conference/workshop papers (43.2%) were the major sources of unique citations in Google Scholar.
Vaughan and Shaw (2008) have studied the citations of 1,483 publications from American Library and Information Science Faculties. The citations were found in December 2005 in the Web of Science and in the spring of 2006 in Google and Google Scholar. Correlations between Google and Google Scholar were high whereas WoS and web citation counts varied. Using Table 1 (page 323) in the publication it can be calculated that a total of about 3,700 citations were found on WoS whereas about 8,500 citations were found in Google Scholar. More citations were found on Google Scholar for all types of publications but whereas the ratio between Google Scholar citations and WoS citations were 8 and 6.4 for conference papers and open access articles the ratio was only 1.6 for publications in subscription journals.
Smith (2008) has investigated the citations found in Google Scholar for universities in New Zealand. There are no direct comparisons with WoS or SCOPUS but the conclusion is that Google Scholar provides good coverage of research based material on the Web.
Using WoS and SciFinder from Chemical Abstracts Service for a random sample of 15 chemists Whitley (2002) reported 3,234 citations in SciFinder, 2,913 in WoS. 58% of the citations were overlapping, 25% were unique for SciFinder and 17% were unique for WoS. For a second random sample of 16 chemists similar results were obtained.
According to Mabe (2003) the ISI journal set represents about 95% of all journal citations found in the ISI database. This conclusion is supported with a reference to Bradford’s Law (Bradford 1950; Garfield 1972, 1979), a bibliometric version of the Pareto Law, often called the Matthew Principle: ‘to him that hath shall be given’ (Merton 1968, 1988). This indicates that citations found in SCI and SSCI are primarily based on the journals covered by these databases.
Bias in source selection and language barriers
When SCI and later SSCI were established it was the ambition to cover the most important part of the scientific literature but not to attempt complete coverage. This is based on the assumption that the significant scientific literature appears in a small core of journals in agreement with Bradford’s Law (Garfield 1972, 1979). Journals were chosen by advisory boards of experts and by large scale citation analysis. The principle for selecting journals has been the same during the whole existence of the citation indexes. New journals are included in the databases if they are cited significantly by the journals already in the indexes and journals in the indexes are removed if their numbers of citations in the other journals in the indexes are declining below a certain threshold. A recent publication provides a detailed description of the procedure for selecting journals for the citation indexes (Testa 2008a).
From soon after the inception of SCI, it has been criticized for being biased toward papers in the English language and those from the United States (Shelton et al. 2009). As an example, MacRoberts and MacRoberts (1989) noted that SCI and SSCI covered about 10% of the scientific literature. The figure of 10% is not substantiated in the publication or in the references cited. However, it is clearly documented that English language journals and western science were over-represented; whereas small countries, non-western countries, and journals published in non-Roman scripts were under-represented. Thorough studies of the problems inherent in the choice of journals covered by SCI have been reported (van Leuwen et al. 2001; Zitt et al. 2003).
A study of public health research in Europe covered 210,433 publications found in SCI and SSCI (with exclusions of overlap). Of the publications 96.5% were published in English, 3.5% in a non-English language, with German as the most common. Therefore the dominance of journals with English language was clearly visible. It is difficult to make firm estimates about how many non-English valuable publications were missed but it is a reasonable conjecture that the number is substantial (Clarke et al. 2007).
Crespi and Geuna (2008) have recently reported a cross country analysis of scientific production. As mentioned above they state that the main source of the most commonly used two proxies for the output of science variables is the Thomson Reuters National Science Indicators (2002) database of published papers and citations. Among the shortcomings in this source is that the Thomson Reuters data are strongly affected by the disciplinary propensity to publish in international journals and that the ISI journal list is strongly biased towards journals published in English, which will lead to an underestimation of the research production of those countries where English is not the native language.
A special report from NSF in 2007 (Hill et al. 2007) contains a short discussion about the coverage of Thomson ISI Indexes. It is mentioned that “journals of regional or local importance may not be covered, which may be especially salient for research in engineering/technology, psychology, the social sciences, the health sciences, and the professional fields, as well as for nations with a small or applied science base. Thomson ISI covers non-English language journals, but only those that provide their article abstracts in English, which limits coverage of non-English language journals”. It is also stated that these indexes relative to other bibliometric databases cover a wider range of S&E fields and contain more complete data on the institutional affiliations of an article’s authors. For particular fields, however, other databases provide more complete coverage. Table 1 in the Appendix of the report presents publication numbers for USA and a number of other countries derived from Chemical Abstracts, Compendex, Inspec and PASCAL for the period 1987–2001. Publications have been assigned to publishing centre or country on the basis of the institutional address for the first author listed in the article. The values for the world can be obtained from the table by addition. According to Chemical Abstracts for 23.0% of the publications the first author was from USA. The values found were for Compendex 25.1%, for Inspec 22.7% and for PASCAL 29.0%. For comparison, the share for USA according to SCI is 30.5% (National Science Foundation 2006). This indicates that SCI is biased towards publications from USA to a higher degree than the other databases. Another possibility is that SCI is fair in its treatment of countries whereas the other databases are biased against USA; this is not a very likely proposition.
In a study of the publication activities of Australian universities Butler (2008) has calculated the coverage of WoS for all publications and for journal articles for publications from 1999 to 2001. The study was based on a comparison between publications recorded in WoS for all publications and for journal articles from 1999 to 2001 and a national compilation of publication activities in Australian universities in the same period. In WoS was found from 74 to 85% of the nationally recorded publications in biological, chemical and physical sciences. The coverage was better for journal articles, from 81 to 88%. For Medical and Health Sciences the coverage in WoS was slightly lower, 69.3 for all articles and for journal articles 73.7%. Again for Agriculture, Earth Sciences, Mathematical Sciences and Psychology the coverage in WoS for all publications was between 53 and 64%, for journal articles between 69 and 79%. For Economics, Engineering and Philosophy the coverage in WoS for all publications was between 24 and 38%, for journal articles between 37 and 71%. For Architecture, Computing, Education, History, Human Society, Journalism and Library, Language, Law, Management, Politics and Policy and The Arts the coverage in WoS was between 4 and 19% for all publications, between 6 and 49% for Journal Articles. These data clearly indicate that it is deeply problematic to depend on WoS for publication studies in Humanities and Social Sciences but also in Computing and Engineering.
In a recent study it is demonstrated that in Brazil the lack of skill in English is a significant barrier for publication in international journals and therefore for presence in WoS (Vasconselos et al. 2009).
A convincing case has also been made that SSCI and AHCI are not well suited for rating the social sciences and humanities (Archambault et al. 2005).
As part of a response to such criticism Thomson Reuters has recently taken an initiative to increase the coverage of regional journals (Testa 2008b). However, the share of publications from the USA in journals newly added to SCI/SCIE is on average the same as the share in the “old” journals covered by SCI/SCIE. This indicates that if there is a bias in favour of USA, it has not changed in recent years (Shelton et al. 2009).
Conference Proceedings have different roles in different scientific fields. As a generalisation it can be said that the role is smallest in the old sand traditional disciplines and largest in the new and fast growing disciplines. In some fields conference proceedings are not considered as real publications, considered as abstracts and not subjected to peer review and are generally expected to be followed by real publications. The proceedings are not published with ISBN- or ISN-numbers and not available on the net. In other fields conference proceedings provide the most important publication channel. Table 8 indicates that conference proceedings are much more important than journal articles in computer science and engineering sciences. In many fields conference contributions are subjected to meticulous peer review. A natural example in our context is the biannual conferences under the auspices of ISSI, The International Society for Scientometrics and Bibliometrics. In many engineering sciences the rejection rate for conference contribution is high. Conference proceedings are provided with ISBN- or ISSN-numbers and often available on the net or in printed form at the latest at the beginning of the conference.
Therefore, in a study of the growth rate of science and the coverage of databases it does not make sense to say no to conference proceedings. It makes sense to include them but be aware of their different roles in different fields when interpreting the results.
Table 4 shows that SCI has a relatively low share of Conference Contributions among the total records. There is however one exception, the complete coverage of “lecture notes in …” series published by Springer, which publishes conference proceedings in computer science and mathematics in book form (Björk et al. 2008).
Thomson Reuters has covered conference proceedings from 1990 in ISI Proceedings with two sections, Science and Technology and Social Sciences and Humanities. However, these proceedings were not integrated in the WoS until 2008. Therefore, the proceedings recorded have not been used in scientometric studies based on SCI and SSCI.
In 2008 Thomson Reuters launched Conference Proceedings Citation Index, fully integrated into WoS and with coverage back to 1990 (Thomson Reuters 2008b). A combination of this new Index with SCIE and SSCI will give a better total coverage. However, if scientometric studies continue to be based solely on SCI and SSCI, the low coverage of conference proceedings there will still cause problems.
The weak coverage in WoS of Computer Science and Engineering Sciences mentioned in “Bias in source selection and language barriers” is probably caused by the low coverage of conference proceedings (Butler 2008).
The inclusion of conference proceedings in databases may cause double counting when nearly or completely identical results are first presented at a conference and later published in a journal article. Again, this is field dependent. In areas where conference proceedings have great importance it is common that publication in proceedings is not followed up by publication in a journal. On the other hand, in areas where conference proceedings are of lesser importance they are often not covered by the databases.
Fast- and slow-growing disciplines
In “Analysis and interpretation of our results” the different growth rates for different scientific disciplines were discussed. There are indications that many of the traditional disciplines, including chemistry, mathematics and physics, are among the slowly growing disciplines, whereas there are high growth rates for new disciplines, including engineering sciences and computer science. Engineering sciences and computer science are disciplines where conference proceedings are important or even dominant. There has through the years been a discussion about and criticism of the coverage in SCI of computer science (Moed and Visser 2007). However, a special effort has been made recently to increase the coverage of computer science in SCI/SCIE, see “Conference contributions”.
Most recently (April 20, 2009), the database INSPEC with a stronger coverage of conference proceedings in the engineering sciences was integrated in the database Web of Science (UC Davis University Library Blogs 2009). The influence of this integration (double counting of conference proceedings and corresponding journal articles as well as better coverage of the literature) is yet to be studied.
Do the ISI journals represent a closed network?
SCI has been the dominant database for the counting of publications and citations. Because of the importance of the visibility obtained by publishing in journals covered by this database and because of the use of the counting values in many assessment exercises and evaluations, it has been important for individual scientists, research groups, institutions and countries to publish in the journals covered by this database. The Hirsch Index (Hirsch 2005) is one example of a science indicator derived from SCI. It is a reasonable conjecture that SCI has had great influence on the publishing behaviour among scientists and in science.
But the journals in SCI constitute a closed set. It is not easy for a new journal to gain entry. One way to do so is to publish papers bringing references to the journals already included. It is important to publish in English since English speaking authors and authors for whom English is the working language only rarely cite literature in other languages. It is also helpful to publish in journals in which most of the publications come from the major scientific countries. No scientist can read everything which may be of potential interest for his or her work. A choice is made and the choice is to select what is most easily available, what comes from well-known colleagues and what comes from well-known institutions and countries.
As mentioned above, Zitt et al. (2003) have made a detailed study of the problems inherent in the choice of journals covered by SCI.
All in all, it is best to get inside but it is not easy. A recent publication about the properties of “new” journals covered by SCI (new means included in 1995 or later) is of interest in this connection. On average the new journals had the same distribution of authors from different countries as the “old” journals (old means included before 1995). Therefore the new journals are not an open road for scientists from countries with a fast growth in publication activity (as for example the Asian Tigers, China, South Korea and Singapore). The new journals are just more of the same (Shelton et al. 2009).
The role of in-house publications, open access archives and other publications published on the net
These forms of publications are fast gaining in importance. The new publication forms may invalidate the use of publication numbers derived from the big databases in measurements of scientific productivity or output and of the growth rate of science. The effect cannot be determined by the data analysed by us. However, there is good reason to believe that a fundamental change in the publication landscape is underway.
Has the growth rate of science been declining?
Price in 1963 concluded that the annual growth rate of science measured by number of publications was about 4.7% (Price 1963). The annual growth rates of 3.7% for Chemical Abstracts for the period 1907–1960 and of 4.0% for Physics Abstracts for the period 1909–1960 given in Table 1 are lower (see Tables 1).
What has happened since then? Tables 2, 3 and 4 show a slower growth rate in the period 1997 to 2006 according to SCI, MathSciNet and Physics Abstracts. Most other databases indicate an annual growth rate above 4.7%. The same can be concluded for the period from 1960 to 1996 but long time series are only available for some of the databases used as basis for Tables 2, 3 and 4.
A tentative conclusion is that old, well established disciplines including mathematics and physics have had slower growth rates than new disciplines including computer science and engineering sciences but that the overall growth rate for science still has been at least 4.7% per year. However, the new publication channels, conference contributions, open archives and publications available on the net, for example in home pages, must be taken into account and may change this situation.