Amazon.com, Inc. announced its fourth quarter results today, counting a 36 percent rise in net sales and an eight percent increase in net income compared to the same period last year. Net sales totaled $12.95 billion for the quarter.

In addition, the company said it sold “millions of third-generation Kindles” during the quarter, keeping figures cloudy. The company did note that Kindle books are now more popular than paperbacks.

Here’s more from CEO Jeff Bezos, from the release: “We had our first $10 billion quarter, and after selling millions of third-generation Kindles with the new Pearl e-ink display during the quarter, Kindle books have now overtaken paperback books as the most popular format on Amazon.com. Last July we announced that Kindle books had passed hardcovers and predicted that Kindle would surpass paperbacks in the second quarter of this year, so this milestone has come even sooner than we expected – and it’s on top of continued growth in paperback sales.”