Almost a third of Americans ages 15 to 24 say they have never had sexual contact with another person, a higher percentage than in a 2002 survey, according to a U.S. government study.

Of those surveyed by the Centers for Disease Control and Prevention, 27 percent of men and 29 percent of women ages 15 to 24 reported being virgins, the Atlanta-based agency said Thursday. In the previous study, 22 percent of males and females 15 to 24 said they never had sex.

The study was conducted because information about sexual activity is needed to plan for HIV, other sexually transmitted diseases and teenage pregnancy, the authors wrote. About half of new STDs occur in 15- to 24-year-olds, according to a previous study cited in the CDC report. The cost of STDs in that population was about $6.5 billion in 2000, the agency said.

“The data should prove useful for planning programs to prevent the spread of sexually transmitted infections and to prevent unintended pregnancy,” the CDC authors wrote.