Previously majority of transitions were homosexual men. Later (around late 70s) around half of transitions became heterosexual men.

I'm not sure this is true, or at least I'm not sure it's necessarily true across the board everywhere in the world. Can you cite your sources please? Such as the research you mention from the 80s with collected info from the 70s. Thanks.

In the Anglophone world, celebrity "transsexual" Christine Jorgensen, an American who surgically "transitioned" in the 1950s, was a homosexual, but the two most famous persons to surgically "transition" in the early 70s - James Jan Morris of the UK & Richard Raskin Renee Richards of the USA - were heterosexual males who had been married to women & fathered children.

ETA: prior to "transition," both Morris & Raskin/Richards were also very stereotypically "masculine" men whose lives had been devoted to manly pursuits beyond siring children: Morris was a much-lauded historian & travel writer with a high-profile job on the nearly all-male staff of the Times (of London) who went on solo expeditions exploring the far corners of the earth, including Muslim countries where he would not have been allowed to travel on his own (or at all) if he had been a woman. Morris was also one of the select macho guys in the male-only crew to "conquer" Mt Everest for the first time in history with Sir Edmund Hillary. Similarly, Raskin/Richards attended a prestigious male-only HS (Horace Mann) & all-male university (Yale), where he was a proverbial "big man on campus" due to his prowess as an athletic star in four sports: American football, baseball, swimming & tennis. This was in an era when there were no school sports for girls & women in the US & in many schools girls & women didn't even have PE classes. Raskin/Richards was scouted by & offered a position with the NY Yankees, something that has never happened to any girl or woman in history. After uni, Raskin/Richards went to medical school at a time when strict quotas were in place to keep the number of women in US medical schools & the medical profession very low in order to insure that medicine would remain an almost entirely male preserve. Richards/Raskin also joined the US military where he became an officer & spent much of his service on the tennis circuit as the US Navy's top-ranked (male) tennis player. Again, this was at a time when there was no tennis or any other sports for any female soldiers or officers in the US military.

In the 60s & 70s, "sex change" clinics/services in the USA associated with big-name hospitals & medical schools such as Johns Hopkins, UCLA, Stanford & Washington University in St Louis MO might have shown a bias towards approving gay males for "transition" surgeries over heterosexual males with autogynephilia. But elsewhere - such as at the world-famous clinic in Casablanca run Georges Burou (the man who invented modern-day penile inversion surgery) & the one in Trinidad, CO in the US run by Stanley Biber - no such preference was shown. So long they had the money, & in the case of going abroad a valid passport, heterosexual males could get a "sex change" from the late 50s, early 60s on just as easily as gay males.

But of course the situation might well have been very different in other parts of the world, such as Scandinavian countries where a majority of "sex change" surgeries would have been done through government-run health care systems.

One of the problems figuring out the proportions of HSTS vs heterosexual males with AGP in the past & how the proportions have changed, or might have changed over time, is that in previous eras, a lot of gay males lived as part-time or FT transvestites without wishing or trying to become "transsexuals" - & heterosexual men with AGP of the same time periods would cross-dress mostly in private or in limited social circles on a PT basis.

Whilst historically the world was indeed hostile to all homosexuals, in the West it was always taken for granted that some of the gay male community were transvestites - & in gay & arty, avant garde circles gay male transvestites were accepted; there was no expectation or pressure for them to have "sex change" surgeries or to claim or pretend that they actually were women. But today, all such persons - gay guys who would have been transvestites in the past & straight guys who are AGP - are lumped together in one undifferentiated, catchall category & dubbed "transgender." What's more, those who are "transgender" today are far more likely than ever in the past to "live as" or claim to be "trans" 24/7/365. At the same time, however, het male cross-dressers likes Pips Bunce & Eddie Izzard who only cross-dress PT are considered to be just as much a part of the "transgender community" as are those who "live in girl mode" FT.