saw income from book sales fall to 60% of total revenue in 2009. Sales of other goods jumped 230% from a year earlier, but still account for less than half of all revenue.

2009年书籍销售收入跌至只占其总收入的60%，与此同时其他商品收入则增长了230%，但是仍然不到其营业总收入的一半。

youdao

In recent years, however, the act of reading has undergone a rapid transformation, as devices such as the Kindle and iPad account for a growing share of book sales. (Amazon, for instance, now sells more e-books than hardcovers.) Before long, we will do most of our reading on screens lovely, luminous screens.

WSJ: How E-Readers Change the Way We Read | Head Case by Jonah Lehrer

If that eventually drives the competition away, Amazon (which is already projected to account for more than half of all U.S. book sales by the end of this year) would be essentially unchecked and able to set whatever prices it wants.

CNN: Will Apple lawsuit mean cheaper e-books?