Amazon famously refuses to disclose the size and profitability of its cloud offerings, hiding Amazon Web Services revenue in a category with co-branded credit cards in its quarterly reports.

However, with the help of analysts and cloud optimization companies such as Newvem, we have a few good guesses.

While Azure is about a billion-dollar business for Microsoft, Amazon likely will almost quadruple that revenue in 2013, with about a third of the $6.2 billion public cloud market in 2012 and an estimated $3.8 billion revenue this year. Even better for Amazon shareholders, some analysts say that AWS is a 100 percent profit business unit.

That dollars-and-cents growth is dependent, of course, on actual cloud services customers, which are predicted to host 11.6 million websites on Amazon in 2013, up sharply from 6.8 million in 2012.┬áMost of those are in the U.S. — just over half — but 34 percent are in Europe and Russia. Nine percent are in South America, with 5 percent in Australia and just 1 percent in Africa.

Here’s all the data, in visual form.

AWS Cloud Usage Improvements - One Year Later