The typical advance for a first novel is $5000. The typical advance for later novels, after a typical number of 5-7 years and 5-7 books is $12,500. Having an agent at any point increases your advance. There is some slight correlation between number of books and number of years spent writing as represented in the 5-12.5 thousand dollar advance shift of an average of 5-7 years.
As I understand it, 5000 books is a typical first print run for all but the most popular novelists. I was recently talking to somebody who worked at a largish Canadian publisher. She reminded me that, to have a ‘best seller’ in Canada, you have to sell 5000 books. Just 5000! It seems to me that the publishing industry gets far too much attention for numbers like those. I know the long tail applies, but it was a reminder of how few novelists really profit from their work.