However, the National Survey of Sexual Health and Behavior, conducted by the Center for Sexual Health Promotion in Indiana University's School of Health, Physical Education and Recreation, also found that many sexual encounters do not involve intercourse, instead culminating in mutual masturbation or oral sex.
"Our data provide answers to these common sex questions," Debby Herbenick, the center's associate director, said in a statement.
The survey of 5,865 people ages 14-94 also reveals that:
-- About 85 percent of men report their partner had an orgasm at their most recent sexual event; while 64 percent of women report having climaxed at their most recent sexual event.
-- Men are more likely to experience orgasm when sex includes vaginal intercourse; women are more likely to climax when they engage in a variety of sex acts.
-- About 7 percent of adult women and 8 percent of men identify as gay, lesbian or bisexual.
-- Forty percent of 17-year-old males reported vaginal intercourse in the past year, but only 27 percent report the same in the past 90 days.
The findings are published in nine separate research articles in a special issue of The Journal of Sexual Medicine.
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