The original article on which this article is based[1] has an interesting chart of median employee tenure for various companies. Amazon is at the bottom, with the median employee leaving after only one year. Google is not much better, with a median employee staying 1.1 years. In contrast, Microsoft employees stay 4 years and IBM employees 6.4 years.
[1] http://www.businessweek.com/articles/2013-10-10/jeff-bezos-a...