how often do women's finals get higher rating than men's finals?
I wouldn't be surprised if that's the case for tennis. There aren't any marketable American players on the men's side.
Even people who don't watch tennis know the Williams sisters. You also have hotties like Sharapova who can get people to tune in. That's also why there are female tennis players doing endorsements, but you don't see too many ads (at least in the US) with male tennis players.
Golf is the opposite. A lot of the top LPGA players are South Korean, while the men's side has Phil Mickelson (the chubby Everyman) and (before the scandal and decline in performance) Tiger Woods.