About half of all students who attend public high schools in New York City are sexually active, and 25% engage in sexual behavior that puts them at high risk of contracting HIV, Newsday reports. The 2003 Youth Risk Behavior Survey, released by the city's health department, asked more than 7,400 students in grades 9-12 about several issues, including sexual activity. The study found that 10% of all the students surveyed had had sex by age 13, that 17% of sexually active students have had more than four sexual partners, and that 24% didn't use a condom the last time they had intercourse. Although the percentage of students who say they did not use a condom the last time they had sex is significantly lower than the 37% national average, the percentage is still "definitely far too high for our liking," says Lorna Thorpe of the health department. Nevertheless, some health officials worry that condom use among students will decline due to a new sex education curriculum in the city that doesn't include demonstrations on proper condom use.