SOURCE: U.S. Department of Education, National Center for Education Statistics, Higher Education General Information Survey (HEGIS), "Fall Enrollment in Institutions of Higher
Education" surveys, 1970 through 1985; Integrated Postsecondary Education Data System (IPEDS), "Fall Enrollment Survey" (IPEDS-EF:86–99); IPEDS Spring 2001 through Spring
2011, Enrollment component; and Projections of Education Statistics to 2020. U.S. Department of Commerce, Census Bureau, Current Population Survey (CPS), October, selected
years, 1970 through 2010.