The following paragraphs present the details of the analytical evaluation of Japan's research level using some of these objective indicators. Also, the subjective evaluation by researchers themselves is included to provide a better understanding about the research level of Japan. It should be noted that, since scientific papers may be cited for some five years after the time of publication, the numerical value of citation frequencies for 1986 was still unclear at the time of analysis by the SLI data base. While the number of papers from each country, with the exception of Japan, remains almost the same. The percentage of citation frequencies of Japanese papers in the world total continued to increase until it doubled in 13 years.
Japan now ranks with European countries.
The United States clearly leads in both the number of papers appearing in scientific journals and in citation frequencies, but it is important to point out that core journals in most scientific fields are primarily published in the United States. This is shown in Chart 22. Chart 22 gives the yearly trends in the total of citation index numbers of papers appearing in the eight fields by country. It can be seen from this comparison that the quality of Japanese papers tended to increase along with that of German and French papers, while those from the United States and the United Kingdom remained at about the same level or showed a decreasing tendency throughout the course of the 13 year period. The Survey of Research Achievements employed the number of invited speakers at international scientific meetings from specific countries as one indicator for the evaluation of research achievements.