differences in the share identifying as predominantly or exclusively homosexual (5% for each sex), but Generation Z men were significantly more likely to refuse to disclose their sexual orientation (7%) than their female counterparts (3%). Significantly more white youth identified as exclusively homosexual (3%) than those of ethnic minority backgrounds (0%) but no other ethnic differences were found. Exclusively heterosexual youths were also less likely to describe themselves as fairly or very active in politics, but they were more likely to believe that they enjoy a better life than Millennials. Among older adults, there were no differences in the share of men (82%) and women (80%) identifying as exclusively heterosexual. But more women than men identified as mostly heterosexual (11% v. 6%), while more men than women identified as exclusively homosexual (4% v. 2%) and mostly homosexual (2% v. 0.4%). Exclusive heterosexuals were more likely to have voted "Leave" on the 2016 UK referendum to leave the European Union, whereas mostly heterosexuals and exclusive homosexuals were overrepresented among "Remain" voters. 2019 The Annual Population Survey reported that an estimated 2.7% of the population aged 16 or over identified as lesbian, gay, or bisexual. United States The demographics of sexual orientation and gender identity in the United States have been studied in the social sciences in recent decades. A 2017 Gallup poll concluded that 4.5% of adult Americans identified as LGBT with 5.1% of women identifying as LGBT, compared with 3.9% of men. A different survey in 2016, from the Williams Institute, estimated that 0.6% of U.S. adults identify as transgender. According to the UNAIDS estimate, the United States was the country with the greatest number of men who have sex with other men. Their estimate did not include information on China. Data scientist Seth Stephens-Davidowitz reported that the actual prevalence of gay men doesn't appear to vary between states in the U.S. because the percentage of Internet porn searches that are for gay male porn are nearly the same in all states, about 5 percent. Stephens-Davidowitz argues that in states where there is a social stigma against homosexuality that "many more gay men are in the closet than are out". Major cities Brazil In 2009, in a survey conducted by University of São Paulo in 10 capitals of Brazil, of the men 7.8% were gay and 2.6% were bisexual, for a total of 10.4%, and of the women 4.9% were