Apple's App Store racked up an all-time high of $240 million in sales on the first day of this year. On the whole, 2016 was a very good year for Apple devs, who earned more than $20 billion for their apps -- up 40 percent over 2015. "Apple has always had the most profitable ecosystem and app market in terms of revenue per user and price per app," said Holger Mueller, a principal analyst at Constellation Research. Super Mario Run was the most downloaded app worldwide on Christmas Day and New Year's Day.