Source: National Center for Education Statistics
From the description:
This report updates a series of NCES reports on high school dropout and completion rates that began in 1988. The report includes national and regional population estimates for the percentage of students who dropped out of high school between 2008 and 2009, the percentage of young people who were dropouts in 2009, and the percentage of young people who were not in high school and had some form of high school credential in 2009. Data are presented by a number of characteristics including race/ethnicity, sex, and age. Annual data for these population estimates are provided for the 1972-2009 period. Information about the high school class of 2009 is also presented in the form on on-time graduation rates from public high schools.
Link to full report (PDF)