A link to this article from The Independent was posted in one of my Forums and I thought you all might be interested.
Take a look at: Pulped fiction: Publishing is booming. So why are writers struggling?
It is most enlightning. Although, I don't think many authors turn to writing nowadays with the illusion they are going to make mega money. A friend of mine told me that an educational book has a shelf life of about five years and then it goes out of print. You have to keep up a large turn over of books to make any money at it.
You know what that means? I best get some work done!