The percentage of the homosexual men attracted to same sex is probably constant though the ages. Austrian and Prussian/German research is interesting, because it was first larger scientific approach to understand homosexuality instead of religious one and is well documented. In the case of Austrian Empire, there was an introduction for new criminal law that was put into the effect in 1855 and survived in most of countries build upon ruins of Austria-Hungary until 1950 or 1961 respectively. Many laws were analyzed by logical approach by inviting the best scientist the Austrian monarchy had from universities of Vienna, Prague and Gratz. Homosexuality was considered for decriminalization and the discussions were led by Dr. Purkyne, who presented the findings that 1:50 of men have permanent, irreversible attraction to same sex and do not wish to change that. However, emperor Franz Joseph was not interested in legalizing it, and the anti-gay law became effective for the next 100 years.
Forty years later, Austria-Hungary was engulfed with antisemitic waves that reached apex during so called Hilsner affair, where Jews were accused of ritual killing of young maidens. The hysteria originated after several unsolved murders of young women (four or five). Another murder of young woman was associated with local Jewish community and population singled out Jews as the perpetrator of the crime with Hilsner in lead. Nationalists from various Austrian nations accused Jews for committing sexual crimes against the Christians and seducing young men to homosexuality to weaken the morals. Czechs and Germans equally blamed Jews that homosexuality was introduced into the society by them. Various studies from arrest reports from 1890's to 1900 proved nothing that the Jews were more inclined to homosexuality than Germans, Hungarians, and Czechs. I think this was done after analysis of 14000 or so arrest records across the monarchy based for the same "crime against the nature". Actually the numbers were equally distributed among the population around 2%. Nationalists refused to accept that study and maintained well to the Nazi era claiming that Jews were recruiting Germans and Czech boys to homosexual behavior.
So any case, Victorian era concluded that 2% of men are totally attracted to same sex gender. That has not changed with present CDC statistics http://www.cdc.gov/nchs/data/nhsr/nhsr077.pdf where in 2013 it was estimated that 1.8% of men are gay.