A government survey of risky youth behaviors shows fewer teens are having sex, NBC News reported. 

The survey found 41 percent of high school kids said they had ever had sex — down from around 47 percent over the last decade. There were also declines in the number of kids who said they had sex before they were 13 and in those who had four or more partners. 

Researchers could not say what was behind the drop or if it marks a new trend. 

The survey was among a series of polls that included 16,000 students at 125 schools, both public and private. Responders were voluntary and anonymous, but required parental permission.