While there are perils around trying to identify exactly what a self-publisher is, Bowker Market Research estimates that approximately 3% of books bought by Americans (and 1% of dollars spent) were by self-published authors. Further, these self-published books accounted for 8% of ebook purchases throughout 2012, and 10% of all adult fiction e-books bought.
One of the things most frequently overlooked in good professional market research material is the "discussion." Sometimes it's shoehorned into a heavily bulleted "executive summary." At other times, it's shunted to the side as "observations."