U.S. slips in gender gap rankings

(Fourth post in a series on the book Matrocracy. Link to first post.)
According to the Associated Press, the U.S. scored lower in the annual Global Gender Gap Report because the percentage of female legislators, senior officials and managers fell in 2007, and the pay gap between women and men widened.

Why is the U.S. 31st in the world in gender equality and not in the top ten? In part, it's a choice voters and potential voters are making. Young single women, whose opportunities are most affected by this gap, are a group that has in the past been least likely to vote.
Link to fifth post in the series.