Its all very complex but most of the pay gap is justified. I mean would you pay a worker more because they are less likely to take sick leave, yes, would you pay a worker more because they are less likely to end up having to take 3 to 9 months off, yes, would you pay a workers more because they are willing to work in life threatening jobs, yes. These are all qualities men have in general when compared to women. The real problem is that Men are undervalued.
The 12% probably refers to the general workforce. As Women are more likely to choose jobs that pay less and Men are more likely to choose riskier jobs with more regimented hours. Men can be paid more than Women for the same job but most burn down to logical reasons. Factory Worker: Strength, Miner: Risk and Strength, these are ones we can all agree on. If I can carry two bricks and you can carry one why are we getting paid the same?
Also another fact to note is that men are much more likely to work full time jobs and that Women are more of a risk in the modern working environment. Frankly there is almost no reason to pay a woman more than a man in any job except communication and emotionally involved jobs. Its biology that determines most pay checks, deal with it, because I will rue the day female miners are paid as much as male, as a clear example of sexism against males and the affirmative action policy in the US is an example of government sponsored sexism and racism against males and whites. I mean surely you should find that more offensive that a government would happily force a company to hire say for example: an ill educated woman over an educated man, all because she is a woman. Peeps need to sort out your priorities.