I'm not surprised at all.
If you look up stats for ereaders the majority of users are women and a large percentage of those women only purchase romance novels for them. Now they can read and fantasize about Fabio all they want on the bus, at the park, etc. and no one has any idea because it's hidden on their kindle screen.
If I wasn't dedicated to other projects right now I would go find a semi-decent ghost writer, use my direct response skills to create some killer titles and covers and try to get those live on amazon ASAP.