As a result of substantial increases in the numbers of Ph.D.s entering the basic biomedical workforce, the median age of the workforce has grown only modestly over the last decade, rising from 43 years in 1987 to 45.7 in 1997. 2 A demographic analysis of the workforce estimates that the median age of the basic biomedical workforce is likely to increase less than a year by 2005 to 46.2 (see Appendix D ).
Unless there is a major departure from current trends in Ph.D. production and retirement, the basic biomedical workforce is projected to grow at a rate of 3.4 percent annually for the next several years. By 2005, women are expected to make up 36 percent of this workforce, which is likely to number more than 128,500 Ph.D.s.
As shown in Figure 2-2 , doctorate production in the basic biomedical sciences was relatively stable from 1975 to 1985 but began to increase at a rapid pace thereafter. By 1997 the number of Ph.D.s awarded in the biomedical sciences reached 5,420.
Over the course of the last two decades, the fraction of women among new Ph.D.s grew steadily, increasing from 23.9 percent overall in 1975 to 42.8 percent in 1997. International students have also become a growing component of new basic biomedical Ph.D.s. In 1975 students on temporary visas were 8.3 percent of new Ph.D.s (see Figure 2-3 ). By 1997 the fraction of students on temporary visas had risen to 21.6 percent.
In contrast, the proportion of underrepresented minorities earning Ph.D.s in the basic biomedical sciences has increased only gradually over the last few decades. In 1997, 4.7 percent of new Ph.D.s were from groups underrepresented in science, up from 2.4 percent in 1975. The absolute numbers represented by these percentages are small: in 1997 only 255 Ph.D.s in these fields were awarded to minorities (see Table G-1 ).
Between 1975 and 1990 the median time to degree in the basic biomedical sciences grew steadily from 6 years to 7.6 years, as measured from entry into postbaccalaureate study (see Table G-1 ). Since then the increase in time to degree has continued, though at a slower pace; Ph.D.s in 1997 spent a median of 7.8 years earning their degrees. As a result, median age at receipt
Unpublished tabulation from the Survey of Doctorate Recipients; available from the archives of the Academies.