lesbian and 1.4% were bisexual, for a total of 6.3 percent. Of the men of the city of Rio de Janeiro, 19.3% were gay or bisexual. Of the women of the city of Manaus, 10.2% were lesbian and bisexual. United States 2011 The Williams Institute at UCLA School of Law, a sexual orientation law think tank, released a study in April 2011 estimating based on its research that 1.7 percent of American adults identify as gay or lesbian, while another 1.8 percent identify as bisexual. Drawing on information from four national and two state-level population-based surveys, the analyses suggest that there are more than 8 million adults in the US who are lesbian, gay, or bisexual, comprising 3.5% of the adult population. Of men, 2.2% identify as gay and an additional 1.4% as bisexual. Of women, 1.1% identify as lesbian and an additional 2.2% as bisexual. These charts show lists of the cities and the metropolitan areas with the highest LGB population in terms of numbers of total gay, lesbian and bisexual residents, based on estimates published in 2006 by the Williams Institute of the UCLA School of Law. Top ranked by percent: Top ranked by total population: Major metropolitan areas by total population: 2015 A 2015 Gallup poll surveying the 50 largest metro areas in the US estimated that the San Francisco metropolitan area had the highest percentage of LGBT people, at 6.2 percent. Research issues Incidence versus prevalence A significant distinction can be made between what medical statisticians call incidence and prevalence. For example, even if two studies agree on a common criterion for defining a sexual orientation, one study might regard this as applying to any person who has ever met this criterion, whereas another might only regard that person as being so if they had done so during the year of the survey. According to the American Psychological Association, sexual orientation refers to an "enduring pattern of emotional, romantic, and/or sexual attractions to men, women, or both sexes", as well as to "a person's sense of identity based on those attractions, related behaviors, and membership in a community of others who share those attractions." Therefore, a person can be celibate and still identify as being bisexual or homosexual based on romantic proclivities. Effect of survey mode According to many a source, from academic researchers to pollsters to market research groups, the population that identifies as LGBT