Amazon (NASDAQ: AMZN) had a surprise hit on its hand with the Echo smart speaker. After releasing it exclusively to Prime members in late 2014, the device proved so popular that Amazon was able to quickly open orders to everyone in the U.S. by the following summer. On Christmas Eve of 2015, the Echo was one of the top five items ordered, according to Amazon’s annual holiday press release. Last year, Echo device sales climbed nine times compared to 2015’s holiday season.