Only 25 percent of women are consistently orgasmic during vaginal intercourse.This bears repeating: Only one-quarter of women reliably experience orgasm during intercourse-no matter how long it lasts, no matter what size the man’s penis, and no matter how the woman feels about the man or the relationship.

This statistic comes not from just one study, but from a comprehensive analysis of 33 studies over the past 80 years by Elisabeth Lloyd in her fascinating book The Case of the Female Orgasm (Harvard University Press).
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