Statistics suggest San Francisco has the highest percentage of gay men among major cities in the world, with a quarter of them HIV-positive, according to Reuters.
William McFarland, head of HIV/AIDS statistics at the city's Department of Public Health, said that an estimated 63,577 gay males aged 15 and above in San Francisco, a city with a total population of 764,000—which represents nearly one in five of the city's males above the age of 15.