Hugh Howey just put out a report (Feb 11, 2014) about the earnings of authors on Amazon. He got together with a tech guy, and they pulled data from amazon regarding the top 1000 books in genre fiction. Then they broke it down by indie, traditional, amazon imprint, and small print publications. There are graphs, and discussion on all of it.
http://authorearnings.com/
There is also a survey, and a petition that you can take/sign.
We're also doing an interview with Howey on http://selfpublishingroundtable.com/ today at 5:30pm PST if anyone is interested.