They tend to run into the big problem that you can make up virtually any number that you want to for many things that get done. However every attempt to estimate says that there is a lot of it, and most is done by women.

However this is a huge issue. For instance suppose that a society goes from mostly single-income families to dual-income and there is a slight increase in family income. Traditional economics shows an increase in family wealth. However the families in question might prefer a few more home-cooked meals and a little less McDonalds! (This is exactly the transition that has happened to the middle-class from the 70's to now. I strongly suspect that real standards of living have fallen, even though statistically there is a slight rise documented...)

Cheers,
Ben