Frugal Dad
I got scared, when I realized that every time I buy such a tiny thing like $0.99 Kindle ebook, I am dealing with a behemoth like this. On the other hand, those 19.5 million customers per day are usually happy with their purchases.
Check also a graphic history of Amazon.
Other infographics I recommend:
State of the BookKindle Fire – 7 vs 8.9 vs 10.1-inch Screen Sizes
Ereaders and Their Impact on Reading HabitsWhich Kindle Models Ship Abroad