The LGBTQIA+ community (Lesbian, Gay, Bisexual, Transgender, Queer, Intersex, Asexual) consists of many different sexual orientations and gender identities. There is little to no information given on the amount of people in the United States who identify within this community as the U.S. Census does not incorporate any questions pertaining to sexual orientation and/or gender identity into its data gathering.
However, research conducted by Gallup reports that in 2016, about 4.1%, or about 10 million Americans, identified as LGBT here in the United States. In 2012, only 3.5%, or 8.3 million Americans, identified as LGBT, so over the span of five years Gallup underwent for data collection, their results show an increase each year. This increase is likely not due to a literal increase in people affiliating as LGBTQIA+, but in changing social norms that are increasingly providing vocabulary and a safe space for members of the LGBTQIA+ community.
Recently, the HRC Foundation (Human Rights Campaign) and the University of Connecticut released the results of a LGBTQ Teen Survey asking questions about the challenges these teenagers face, including questions concerning mental health. 12,000 LGBTQ teens, ages ranging from 13 to 17, from all 50 states answered the survey. A few results stated that 77% of LGBTQ teens reported feeling depressed recently, 70% reported that recently they have been feeling worthless and hopeless and 67% reported hearing family members making negative comments about those who identify as LGBTQ.