http://recode.net/2015/04/23/amazon-reveals-aws-is-a-nearly-5-billion-business-and-is-profitable/:

The company, which hasn’t previously broken out AWS results, said its Web services business grew 49 percent in 2014 to $4.6 billion in revenue. In the first quarter, AWS revenue grew 49 percent to $1.6 billion. AWS operating margin was 17 percent in the first quarter, down from 23 percent in the same period last year. Glad I chose AWS over the competition several years ago when there was actually a choice to make.