FAA estimates that as many as 7,500 small commercial drones could be operational within five years in U.S. airspace.
There are 4,000 different unmanned aerial vehicles in circulation on the global market, most built by the United States.
Manufacturers, according to an IHS Industry Research and Analysis report. The United States spends more than half of the total research and development money spent worldwide on drone development.
Source:LiveScience