 The CDC said in 2007, 35% of US high school students were currently sexually active and 47.8% of US high school students reported having had sexual intercourse.In 2017, the percentage sexually active was down to 28,7%, and the percentage who had ever had intercourse was 39.5%.According to a 1994 study, every year an estimated one in four sexually active teens contracts a sexually transmitted infection (STI).