Quote:
Nationwide, Gallup says, 3.6 percent of adults consider themselves gay, lesbian, bisexual or transgender. [...] Gallup’s numbers are based on surveys of 374,325 adults across the 50 largest metropolitan areas, conducted between June 2012 and December 2014. The margin of sampling error for each of the metropolitan areas is no more than plus or minus 1 percentage point.
Note that the numbers roll everyone up in one basket -- they don't distinguish L from G or B or T. I don't know how long the link will stay good, but this is the article: