Solid analysis by GenderGapGrader, worth a read:

women account for approximately 5.44% of airline commercial pilots globally.

This is really low, wow—and the USA is below that average!

The percentage of currently enrolled female student pilots shows some signs of hope: 12.9% in Japan, 12.5% in India and 12% in the USA. 

It's clearly not good enough. 

And I'm simply astonished to read that some people would refuse to board a plane piloted by a woman. Maddening.