Marketing for a book proposal

[LadyDani82]

Does anyone know of a site where you cna find statistics and facts on a book that you want to mention as competion in a book proposal?
The stats i'm looking for are book salles from year to year, demographics of the books readers,how much a writer was advanced for their book, etc.

[writerfromtheledge]

You can sometimes find out advance info through publishers marketplace. Not sure about demographics and sale, though.