Tuesday is Equal Pay Day — which symbolizes how far into 2011 women would have to work for their 2010 pay to finally catch up to men's, according to the National Committee for Pay Equity. Over the span of a 40-year career, the pay gap adds up to a "shocking" $713,000, according to the Center for American Progress, although there's still debate over whether the difference is due to "discrimination or different career choices." Here, a brief guide, by the numbers:

How much less a woman earns compared to a man over a 40-year career, according to the Center for American Progress Action Fund

The gender pay gap in the legal profession, where it's at its largest. While women make up more than half of the legal profession, many of them work in lower-paying legal support jobs, and not as lawyers and judges.

Average number of years that "31 percent of highly qualified women voluntarily leave the workforce," according to the Center for Work-Life Policy

Percent of a women's future earning power lost for taking such a "career detour"

Percent of the average man's salary that his female counterpart makes one year out of college. "The gap between men's and women's salaries begins immediately upon entering the workforce," says Sarah Green in the Harvard Business Review.

Percent of board seats at Fortune 500 companies held by women in 2010. That's "an inexplicable statistic given the number of available qualified female candidates," say Douglas A. McIntyre, Michael B. Sauter, and Ashley C. Allen in The Atlantic.

Nearly 2/3
Share of workers in the 10 lowest-paid occupations who are women

Nearly 1/3
Share of workers in the 10 highest-paid occupations who are women

Amount full-time female employees are paid for every dollar their male counterparts make, according to census data

Amount full-time female employees were paid in 1970 for every dollar their male counterparts make. "Forty years and 18 cents," says Marlo Thomas in The Huffington Post. "A dozen eggs has gone up 10 times that amount."

Sources: Business Insider, Harvard Business Review, Dayton Business Journal, Wall Street Journal, Huffington Post