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Amazon’s cloud computing business is bigger after 10 years of operation than Amazon itself at the same milestone, and is on its way to being a $10 billion annual business this year, CEO Jeff Bezos wrote in a letter to shareholders today.

Amazon Web Services “is bigger than Amazon.com was at 10 years old, growing at a faster rate, and — most noteworthy in my view — the pace of innovation continues to accelerate,” Bezos wrote, adding that the unit added 722 new features in 2015, which amounted to a 40 percent increase over the prior year.

Last month AWS observed its 10th year of operations, and was the bright spot in an otherwise disappointing fourth-quarter report in January. The unit clocked $7.9 billion in revenue in 2015, amounting to more than 7 percent of Amazon’s overall sales, with an operating margin of 24 percent.

“Many characterized AWS as a bold — and unusual — bet when we started,” Bezos wrote. “We could have stuck to the knitting. I’m glad we didn’t.”