The Centers for Disease Control and Prevention is out with a survey about high school students about their sexual behavior.

Some 15,000 students completed anonymous, self-administered questionnaires that included identically worded questions about sexual intercourse, number of sex partners, condom use and injection-drug use.

The results are mixed.

From 1991 to 2007, the percentage of U.S. high school students who ever had sexual intercourse decreased 12 percent.

Among those who are sexually active, condom use went up 33 percent for boys and girls, and all racial groups.

But it's not clear if the increased condom use is having an effect on sexually transmitted diseases.

Gonorrhea is up slightly among high school students. Cases of HIV are up too.

Teen births were dropping for a while, but are increasing slightly.

During 1995-2007, the use of intravenous drugs held steady at 4 percent. However, there appeared to be an increase in injection-drug use among black and Hispanic students.

The CDC report said additional efforts to reduce sexual risk behaviors, particularly among black, Hispanic and male students, must be implemented to meet the federally funded Healthy People 2010 national health objective for adolescent sexual behaviors and to decrease rates of HIV infection and STDs.