borderlands empirically demonstrates that is not a very large populace, or perhaps that populace was enjoying serendipity at borderlands then buying from amazon
ps -- some of that serendipity is available online too; see eg the big ideas -- authors talking some aspect of their novels -- on John Scalzi's site. Of the fiction books I've read in the last 3 years, probably 80% of them have come from reading these posts. http://whatever.scalzi.com/category/big-idea/