I thought I would provide percentages for sales numbers for my e-book, iOS 8 for Users and Developers. It has been on sale since Wednesday, September 17th. These are sales percentages for just two days, and this does include 16 days worth of pre-orders. This chart is comprehensive between both Amazon and Apple. Here are the links for purchase Apple (ePub), Apple (iBooks), or Amazon (ePub).

As you can see the United States has purchased the largest percentage of the e-books. To make it easier to see percentages, given such a disparity, I've created another chart.

This is a chart with percentages not including the United States. Hence, the percentages for this graph are based on 20% of total sales.