"...Women earned less than men in all 20 industries and 25 occupation groups surveyed by the Census Bureau in 2007 even in fields in which their numbers are overwhelming. Female secretaries, for instance, earn just 83.4% as much as male ones. And those who pick male-dominated fields earn less than men too: female truck drivers, for instance, earn just 76.5% of the weekly pay of their male counterparts. Perhaps the most compelling and potentially damning data of all to suggest that gender has an influence comes from a 2008 study in which University of Chicago sociologist Kristen Schilt and NYU economist Matthew Wiswall examined the wage trajectories of people who underwent a sex change. Their results: even when controlling for factors like education, men who transitioned to women earned, on average, 32% less after the surgery. Women who became men, on the other hand, earned 1.5% more. [...] Over a period of 15 years, according to a 2004 study by the Institute for Women's Policy Research (IWPR), a full 52% of women in the prime earning age range of 26 to 59 go through at least one full calendar year earning nothing at all, compared with just 16% of men. [...] Yet no matter how you interpret the numbers, there are a few stubborn percentage points that can't be explained away. Economists and advocates alike speculate that these are the products of slippery factors like discrimination conscious or not. A 2000 study, for instance, famously found that after symphony orchestras introduced blind auditions, requiring musicians to perform behind a screen, women became more likely to get the gig." (source: http://content.time.com/time/nation/article/0,8599,1983185,00.html)

Commence the downvoting Internet! :D