According to a u. s. national survey conducted in 2009, by age 20, percent of u. s. youth have engaged in sexual intercourse.

In the survey made by United States in the year 2009, by age 20, the percentage of youth in US that are engaged in sexual intercourse is 77%. The percentages in the national level are as follows, for the twelfth -graders are 49%, 40% of eleventh- graders, 29% of tenth-graders and for the 9th graders, 21% are sexually active. These are all according to Eaton and others, 2010. 

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