The state of savings among single American women

How many American women are saving money in the expectation that they will be contributing 1/2 to a future home and everything else when they are married (or even before, if they've found someone willing to commit to them apart from the formality of a ceremony)? Those trips to foreign countries and exotic locales can be rather expensive, and many run up their credit card bills on shopping. What number are rather carefree in their spending habits, believing that when the time comes they will be able to find a man who will bear the responsibility of paying for the house and other marital assets?