"But because most death investigators do not collect data on sexuality or gender identity, no one knows how many gay and transgender people die by suicide each year in the United States..."

It says in "No One Knows How Many L.G.B.T.Q. Americans Die by Suicide/Death investigators in Utah are among a handful of groups trying to learn how many gay and transgender people die by suicide in the United States" (NYT).

So often we hear policy arguments based on the likelihood that transgender people will commit suicide as — as if the number is well known (and as if we also know why they commit suicide).

The absence of data is especially unfortunate now, [researchers] said, when assumptions about suicide rates among L.G.B.T.Q. groups are frequently thrust into high-stakes political debates. Some L.G.B.T.Q. advocates have warned that bans on gender-affirming care for transgender minors will lead to more suicides, for example, while some Republican lawmakers have claimed that deaths by suicide are rare.... 

Although studies have reported a high rate of suicidal thoughts and suicide attempts among lesbian, gay and transgender people, that doesn’t necessarily mean a high rate of suicides. [Michael Staley, a sociologist who was hired to lead the data-collection effort in the Utah medical examiner’s office,] noted that although women have a higher rate of suicide attempts than men do, men have a much higher rate of dying by suicide, partly because they have more access to guns....