It is very well documented. As Ms. Kerr was saying earlier, we do not have the figures, but when it comes to sponsorships for men's and women's sports, it is day and night. In fact, we almost cannot compare the two situations, because there are so few sponsorships on the women's side.
That brings us to the question of media coverage of women's sports. Sponsors are looking for visibility, so if there is no media coverage of women's sports, it will be much more difficult to attract them. Television gives us women's tennis, because the athletes are wearing skirts and are pretty, and a bit of golf and some figure skating. Otherwise, we do not see any. The importance the media assign to men's sports as compared to women's sports creates an incredible gap.