According to a 2006 study, men and women in the United States first experienced sexual intercourse at age 17 on average.
A 2007 study by Mathmatica Policy Research for The Kinsey Institute notes that 49% of women lose it by age 17, while 46% of men lose it by the same age.
Assuming this holds true with the population recorded in the 2010 Census, here’s how that would break down:
Women:
The 2010 census recorded over 10M women ages 10-14, and over 10.7M women ages 15-19. If we assumed that each age spreads equally (i.e. the same number of 10-year-olds as the number of 19-year-olds), there would be approximately 2M women for each age 10-14, and 2.140M women for each age 15-19.
Let’s also assume that virginity loss commences at adolescence, at age 13. Within the two age brackets, ranging ages 13-17, approximately 10.42M women have lost their virginities during this timeframe.
Putting the 10.42M over the combined age brackets totaling approximately 20.7M yields approximately 50%.
Men:
The 2010 census recorded over 10.5M men ages 10-14, and over 11.3M men ages 15-19. Again, we’re assuming that the various ages spreads equally: Approximately 2.1M men for each age 10-14, and 2.26M men for each age 15-19.
Again taking the 13-17 age range, approximately 10.98M men lose their virginities during this period. This amounts to approximately 50% of the combined age bracket range.
While the average age for virginity loss in women has stayed relatively flat in the three years since 2007 to 2010, men’s average age for the same rite of passage has risen slightly. This could be due to the fact that men are losing it slightly earlier within the age spread, or that there are simply more men within this age range.