In Sweden it's crime novels. Always crime novels. I don't know if it's the cold, or if we're fed up with the Law of Jante, but we go around and imagine ways to murder each other all day.
Romance/erotica is king despite the bad wrap it gets. They outpace any genre by a country mile. After that I believe is crime/mystery, and then sci-fi/fantasy stuff. Children's and YA are also big money.