Up to a few adjustment factors, you'd expect the average nanny to cost the same as the average woman's salary, unless nannies have large economies of scale. Th

Up to a few adjustment factors, you'd expect the average nanny to cost the same as the average woman's salary, unless nannies have large economies of scale. Those adjustment factors would be things like -- what percentage of women have children, how many children do they have, how many children does the average nanny care for... We could work through the various supply and demand factors, but, basically, whether compensated formally or not, if you hold the fertility rate fixed, then you also hold the amount-of-childcare fixed. There's some kind of conservation rule at work. You can make the model a little bigger by including all the raising-of-children in those countries that are net exporters of people. Which there will be fewer and fewer of.