There are a lot of drones in the United States — and the number is growing rapidly. More than 770,000 U.S. drone registrations have been filed in about 15 months, the Federal Aviation Administration’s Michael Huerta said at a conference on Monday. That’s an increase of 100,000 in the past three months alone. At the Consumer Electronics Show in Las Vegas in January, FAA administrator Huerta said the agency had recorded 670,000 drone registrations at that time, as Recode noted. “We’re ushering in a new age of American aviation: the unmanned aircraft era. And it’s moving at a quicker pace than anything we’ve seen before,” Huerta said in a speech at the second annual FAA Unmanned Aircraft Systems Symposium on Monday. While this figure has often been reported as the number of drone owners, the breakdown is a bit more complicated. Individual “hobbyists” receive just one ID number for all the drones they own, while anyone other than hobbyists — which primarily consists of commercial users — must register each drone separately. The FAA made it mandatory to register drones starting in December 2015, and the agency expects usage to keep climbing. Last week the group released estimates predicting the number of small hobbyist drones in the United States will triple to about 3.55 million in 2021 from 1.1 million in 2016.