Percentage of Non Marital Births by Age of Mother
Source: Source: Stephanie J. Ventura and Christine A. Bachrach, "Nonmarital Childbearing in the United States, 1940-99," National Vital Statistics Reports 48, no. 16 (Hyattsville, MD: National Center for Health Statistics, 2000) and CDC data
http://www.cdc.gov/nchs/data/hestat/prelimbirth04_tables.pdf#search=%22cdc%20unmarried%2020-24%22