I have no statistics, but from my own observance, I think generally women just don't do martial arts for social reasons. In the town where I live, the council subsidize a scheme where the children have a choice in following introductory courses in all sorts of sports, such figure skating and horse riding. As far as I know, every child at a primary school in this town receives a list of the possibilities. My daughter enrolled in the judo. Of the 18 children, on the course, only 4 are girls. On the other hand, the ballet classes my daughters follow have long waiting lists and I think there are only one or two boys in the junior classes. And talking to my female friends (those not into Aikido) they seem to frightened of the physical aspects of martial arts, of getting hurt. So they don't even get as far as going to a dojo, let alone ever knowing whether males dominate there or not. However, I think this attitude might change slowly if there enough female role models. Perhaps some one ought to make a movie with a female aikidoka who kicks ass but retains her femininity, like Micheline Tissier-Valliant Sensei. After all, however good Steven Seagal's aikido is, most girls don't actually want to be like him.