Working, in America, is in decline. The share of prime-age men — those 25 to 54 years old — who are not working has more than tripled since the late 1960s, to 16 percent. More recently, since the turn of the century, the share of women without paying jobs has been rising, too. The United States, which had one of the highest employment rates among developed nations as recently as 2000, has fallen toward the bottom of the list.