[sammyg2]

Take a good look at when they started the 401(k) program.

People started putting away a portion of their salary as a retirement program in the early 80's, and it usually ends up being invested in the stock market through mutual funds etc.
The more we save, the more we invest, the more the price of stocks goes up.
That results in a buttload of money being put into the market. In other words, we are investing in our own country.

edit: aw crap, Vincent beat me to it.