for example, fewer than 10% of life scientists receiving PhDs were women. By 1996, the corresponding fraction was over 40%. In contrast, the number of men receiving life-science PhDs—after rapidly rising in the 1960s—actually declined from 1971 to 1987 and has only modestly increased since then. Although there has been a doubling in the fraction of life-science PhD recipients who are members of minority group over the last 20 years (table E.1), the absolute numbers remain very small—rising from 96 in 1973 to 341 in 1996.
The second notable change is the increase since 1987 in the number of degrees awarded to citizens of other countries. As shown in figure 2.3 and table E.5, the number of foreign citizens (holding permanent-resident status or temporary visas) earning life-science degrees at US universities more than doubled from 1987 to 1996 (from 1,127 to 2,947). The percentage of life-science PhDs who are foreign nationals with temporary visas peaked at 28.2% in 1993 but declined somewhat thereafter. That is almost certainly an artifact attributable to the passage of the Chinese Student Protection Act of 1992, which permitted Chinese nationals temporarily residing in the United States to change to permanent-resident status; many Chinese students who have earned PhDs since 1992 have been counted in the US citizen and permanent-resident category. Figure 2.3 shows that when the number of temporary residents receiving PhDs dipped after 1993, the number of permanent residents increased sharply and that the sum of these two classes of foreign nationals rose at a steady pace from 1989 to 1996.