The progress in closing the gender wage gap has  stalled — but not for the reasons you might think.

The problem is not that women’s earnings aren’t keeping pace with men’s. In fact, over the past decade, men’s wages have fallen. The problem is that women’s wages haven’t grown much.

That finding is highlighted in a new report to be released today by the Institute for Women’s Policy Research. In 2003, the median usual weekly earnings for women who worked full-time was $699, adjusted for inflation. Men earned $880 a week. The ratio of female-to-male earnings was 79.4.

Fast forward to 2013. Men’s wages fell $20 to $860 over the decade. But despite that drop, the earnings ratio only crept up to 82.1. The culprit? All but stagnant wages for women, which rose $7 to $706.

“Basically, no progress,” said Heidi Hartmann, IWPR president.

In the 1980s and ‘90s, women’s rising real earnings drove much of the narrowing of the gender wage gap. Men’s earnings fluctuated during that period, up some years and down others. But women steadily brought home more bacon. Median usual weekly earnings jumped from $565 in 1980 to $617 in 1990 and then to $667 in 2000. The trend holds using annual earnings as well, though data from last year is not yet available.

Source: Chart by Institute for Women’s Policy Research. Annual median earnings data from Census Bureau. Median usual weekly earnings data from Bureau of Labor Statistics.

In an ideal economy, wages for both men and women would be rising, with the latter at a slightly faster pace to close the gap. But that’s not how the real world worked. Hartmann said that improvements in the wage gap since 1975 have generally occurred when women’s earnings were rising and men’s were steady or falling. Now that women’s wages are stalling, so is progress on the wage gap.

Hartmann surmises some of the factors holding back wages could be the levelling off of the number of women in the workforce, particularly in traditionally male jobs. In addition, historically female jobs, such as teachers and clerical workers, fared poorly in the aftermath of the Great Recession.

“The fact that it’s gone on so long is discouraging. Women are getting the education. They’re out there working,” Hartmann said. “Where’s the progress?”