More evidence arrived Tuesday of the shift in worldwide research capacity that is diminishing the relative role of the United States.

Between 2002 and 2007, the share of the worldwide research population in the United States fell to 20.3 percent from 23.2 percent, according to a new report from the United Nations Educational, Scientific and Cultural Organization.

During that same period, the share of the research population in China grew to 20.1 percent from 14.0 percent, nearly overtaking the United States. Because of overall growth in the researcher population worldwide -- to 7.1 million from 5.8 million -- the relative decline in the United States does not mean that there are not as many American researchers, just that other countries saw a comparative gain. (And as a share of its relative population, the U.S. researcher base is much larger than that of China.)

Over all, during the period studied, the number of researchers grew by 56 percent in developing nations and by 8.6 percent in countries that are already developed.

The definition of researchers used by the study would include but by no means be limited to those in academe. Researchers, the study says, "are professionals engaged in the conception or creation of new knowledge, products, processes, methods and systems and also in the management of the projects concerned."

Unesco's study also found wide variation in the gender mix among researchers. Worldwide, the study found that women make up 29 percent of all researchers, but gender breakdowns were not obtained for a number of countries -- including the United States and Britain -- with many female researchers. In Asia, women make up only 18 percent of researchers, while the figure reaches 46 percent in Latin America, where gender parity has been reached in five countries: Argentina, Cuba, Brazil, Paraguay and Venezuela.

The following table shows the relative share of the world research population in the two years studied and the most recent data for the number of researchers per 1 million total population. Japan leads in that category, followed by the United States. The Unesco data (and this table) mix regions and countries, including countries that make up various regions.

The World Research Population