We have done work on that. It's clear that it's a troublesome situation.
The fact is that even though education levels are at par or higher at times than men, as you say, it's not translating into income. Often women undertake other responsibilities, as we all know. They are the ones who still do most of the unpaid work in our society; although with parental benefits and other possibilities, men are taking up the challenge more than they used to. Women are also often in non-standard work because of caregiving responsibilities not only for young children, but for the elderly, the sick, and the more vulnerable in our society. At times they are involved in occupations that are not necessarily generating revenue at the same rates as others.
I would ask Zeynep Karman, who is the director of the research directorate and is responsible for the policy research fund, to give you more information on some of the research we've done that you might be interested in reading.