NOTES: Citation counts based on a 3-year period with 2-year lag, e.g., citations for 1999 are references made in articles published in 1999 to articles published in 1995-97. Citations on fractional-count basis, i.e., for cited articles with collaborating institutions from multiple countries/economies, each country/economy receives fractional credit on basis of proportion of its participating institutions. Detail may not add to total because of rounding. EU-15 consists of 15 EU countries before expansion of member countries on May 1, 2004 (listed countries plus Luxembourg). Germany data for 1992 include former East Germany. China data include Hong Kong. Czech Republic data for 1992 and 1996 include former Czechoslovakia. SOURCES: Thomson ISI, Science Citation Index and Social Sciences Citation Index, http://www.isinet.com/products/citation/; ipIQ, Inc.; and National Science Foundation, Division of Science Resources Statistics, special tabulations.
Scource: Science & Engineering Indicators – 2006