According to Wikipedia, “ multiple studies from OECD, AAUW, and the US Department of Labor have found that pay rates between males and females varied by 5–6.6% or, females earning 94 cents to every dollar earned by their male counterparts, when wages were adjusted to different individual choices made by male and female workers in college major, occupation, working hours, and maternal leave.”
A new meta-analysis by Marieka Klawitter of University of Washington looked at 29 studies and found a 9% earnings premium for lesbians over heterosexual women. http://onlinelibrary.wiley.com/doi/10.1111/irel.12075/full
9% premium vs. 5–6.6% deficit? Neat.