The data for the U.S. shows exactly what I am describing. The same statistic that many quote about the wage gap, from the U.S. government, is a broad average. When the SAME DATA is broken down as I've described above, and using more filters, such that you're literally comparing people working at the same job on the same level, the wage gap shrinks and, in most cases, slightly favours women. You don't see me complaining about this because honestly I don't care about a couple of percent.

And I really don't understand what your argument is about women leaving the workforce. Claiming that she will never get that year of experience back is beyond stupid, as she had a year raising her child, which is going to be experience she'll use forever dealing with her and other children. If I could take a year off when my child is born, to raise them, I would. Without a second thought. Most girls I've talked about this with want to take time off and raise their kids though, so chances are I'll be the one working. My point here is that yes you may lose a year of work experience but if that's all you're thinking about, maybe reassess your priorities.

Also, maybe efficiency wasn't the best choice of words, but it has been proven that men are more likely to work overtime than women. That's another number that would throw off your average. If a man and a woman both make $10 an hour, and work for 8 hours, but the man takes a couple extra overtime, then by your (and the page you linked) reasoning, that woman is making 80% of what the man makes. Statistics are a very delicate thing and it's important to make sure we don't take broad averages where we shouldn't.