The gender-gap exists in freelance pay, too

This survey of freelancers shows there's a gender gap in earnings, even for independent contractors. I'm guessing this data is all U.S.-based, but no doubt the stats are similar in other Western countries. This blog post about the survey's results points out that the gap may be partly due to earnings being based on previously-held full-time roles, where we know there's a gender-based pay gap.