A 'damage novel' might be a term used to describe a novel that explores the consequences of damage. It could be damage to individuals, like in a psychological thriller where the main character's mind is damaged due to some past event. It may also deal with damage to a community or a culture. In many war novels, for instance, we see the damage to the social fabric, values, and traditions of a community. The story then often revolves around how the characters either come to terms with this damage or try to repair it.
It's hard to give an exact percentage because it can vary greatly depending on different markets and publishing statistics. But generally, a significant portion of books published are fiction.
Estimating the percentage of fiction books is tricky. Different studies and sources might offer different figures. However, it's safe to say that fiction often makes up a considerable chunk of the book industry.