Female lawyers make less than male lawyers. You might have already known this, but the numbers in a comprehensive, 12-year survey published last week expose the differences in stark detail.

Women at the largest firms make 66 percent of their male colleagues’ incomes, according to the latest results of the “After the J.D.” study, which tracked more than 5,000 lawyers across the United States who were admitted to the bar in 2000. That amounts to a $100,000 gap between the $191,000 median income for women and $290,000 for men at firms of more than 250 lawyers.