according to wiki..
As of January 2017, the global participation rate of women in national-level parliaments is 23.3%
While you may find an outlier like Rwanda that has a parliament with more than 50% women, it is only because most of the men were slaughtered in the Rwanda genocide, and new babies haven't replaced the lost generation.
When women make up 50% of the voters, the only plausible reason for the lack of women can only be a disinterest of women voting for women, assuming there is no voter intimidation. (we saw this with Hillary)... So why are most parliaments in liberal and free nations still around 30% women participation?
It's the same reason why there are more men in jail than women.