You see a decent number on ATL-NYC, particularly ATL-EWR. Not world-beating numbers, but that route gets its share of traffic, especially on certain weekends.
HKG-BKK also sees a lot of GGG traffic, especially on certain weekends.
I would say you'll see the highest proportions on routes into cities where there's a gay event happening: Palm Springs at Easter, New Orleans at Halloween, New York at Pride, BOS-Ptown during summer....