Estimates of the prevalence of homosexuality vary, but range somewhere between 3 percent and 13 percent, depending on the definition of homosexuality used. The number of people engaging in homosexual behavior is likely much smaller than the number of people experiencing homosexual attraction or fantasies. In a 1995 study by Randall Sell, James Wells, and David Wypij, about 3 percent of females and between 5 percent to 11 percent of men across the United States, the United Kingdom, and France reported homosexual behavior in the past five years. About 8 percent of males and 10 percent of females reported homosexual attraction but not behavior since age fifteen. Combining measures of attraction and behavior, about 18 percent of both men and women reported either homosexual attraction or behavior since the age of fifteen.