I think I can shed some light on this subject with the help of everyone's favorite website --IGN (sarcasm.)Using personal experiences outside of the game as a basis for numbers is not a good idea.
I remember a podcast on IGN within the past year where they were talking about the 5 online games with the highest percentage of female players. The highest was CoD, which was 20% female. I think the other online games were WoW, Dota 2, LoL, and one game I forgot. Obviously that implies less than 20% of WoW players are female. And yeah, they were quoting a statistic of some kind, not just pulling it out of their ass (but I don't blame you if you don't believe me, lol.)