So says Slate, which has a chart showing the male participation rate falling from over 87% in 1948 to 73% now.
The trend waxes and wanes to an extent, for what I imagine are a variety of reasons. But the secular trend is clear and the reason for it seems obvious. There's more to life than work and gross domestic product. America is better at doing stuff in 2012 than it was in 1962. We've used that improved know-how in part to amass more stuff per capita than people had in 1962. But we've also used that improved know-how to enjoy much cleaner air than prevailed in 1962. And we've used that improved know-how to do less work than people did in 1962.