NFL's Female Fans

For years, men were thought to be the sex that was more likely to care about football. In recent years, there has a dramatic increase in women that consider themselves fans of the game. How exactly did this come to be, because stereotypically a football fan was a male. Now, one could make the argument that there are just as many female fans of the NFL as men. There's only one question, what changed the female perspective on the game?