Well The United States has one of the biggest, if not the biggest population of Homosexual/LGBTQ+ groups when compared to other countries.
Now whether this is so because of social openness on the issue, or funding for research can be debated but I think the real number on average given any general populace in a vacuum is probably 2% realistically.
Image source 1:
https://www.statista.com/chart/30142/respondents-who-identify-as-lgbt--in-selected-countries/
Image source 2:
https://worldpopulationreview.com/country-rankings/lgbtq-population-by-country
Image source 3: