Note: Trends in non-marital births may be affected by changes in the reporting of marital status on birth certificates and in procedures for inferring non-marital births when marital status is not reported. Prior to 1980, racial classification was reported on the basis of the race attributed to the child; thereafter it was based on the race of the mother. For Hispanics the graph lines are partially in bold to distinguish between the interpolated data in the two intervals 1980-1985 and 1985-1990 from the annual data from 1990 onward.
Source: National Center for Health Statistics, “Nonmarital Childbearing in the United States, 1940-1999,” National Vital Statistics Reports, Vol. 48 (16), 2000; “Births: Final Data for 2009,” National Vital Statistics Reports, Vol. 60 (1), November 2011, http://www.cdc.gov/nchs/products/pubs/pubd/nvsr/nvsr.htm.