Based on a 2019 report by sociologist Taylor Whitten Brown for The Art Market using internal data from Artsy, median prices for female versus male works of art created after 1999 shows female works are worth 31% less than male works in North America*. The study gathered data from across the globe. In Africa and the Middle East, the gap is 10%, in Oceania, it is 16%, Asia and Latin America have a 22% gap, while in Europe, the gap is 26%. This shows that the gap in North America is the highest among all and that women's work is systematically undervalued.
The consistency of this wage gap appears in another study** that shows the difference in earnings between working men and women in Canada. If you add up the earnings of all working women, that sum is about 31% less than the combined earnings of all working men. For women of colour, the gap is 37.5%, while it’s estimated that Indigenous women earn a whopping 54% less than men.
*Brown, Taylor Whitter. "Why Is Work by Female Artists Still Valued Less Than Work by Male Artists?" https://www.artsy.net/article/artsy-editorial-work-female-artists-valued-work-male-artists. March 8, 2019. (accessed March, 28, 2019)
**McIntyre, Catherine. "These are the key numbers that explain the wage gap for women." Macleans.ca. https://www.macleans.ca/society/pay-equity-statistics-canada/. Feb 8, 2018. (accessed April 29, 2019).