When economists measured the amount of work someone does, it was almost always "market" labor. That means work you are paid for. Eventually, they allowed women to become economists, and it was realized that a great deal of production and labor happens outside the labor market. For instance, making pancakes as a short-order cook counts as labor, but making pancakes for your family does not.
Here's an interesting chart showing the market and non-market labor of men and women in a bunch of different countries.
Things to notice: Women in the Netherlands do more non-market labor than any other group, although women in Nepal, Kenya, and Indonesia do more work overall.
Men and women in the US, surprisingly, do similar amounts of work. Men in the US and UK do similar amounts of work, but women in the UK do more non-market labor than their US counterparts.
I'm sure you'll discover your own interesting facts in this chart. (Click for larger.)