"In 2005, 47 percent of high school students (6.7 million) reported having had sexual intercourse, down from 54 percent in 1991. The rate of those who reported having had sex has remained the same since 2003.

Of those who had sex during a three-month period in 2005, 63 percent -- about 9 million -- used condoms. That's up from 46 percent in 1991.