The consumer market for unmanned aerial vehicles, better known as drones, is off to a “very strong start,” research firm Tractica said in a report Thursday.

Tractica forecasts that worldwide consumer drone shipments will sky from 6.4 million units in 2015 to 67.7 million units annually by 2021.

Last year, global sales of consumer drones reached $1.9 billion and will continue to grow rapidly over the next few years, Tractica said. The Boulder, Colo.-based firm predicts that the consumer drone market will reach $5 billion in sales by 2021.

Consumers are using drones to taking breathtaking aerial photos and videos and to play aerial racing games.

Key industry players include China’s DJI and Yuneec, France’s Parrot, and U.S.-based 3D Robotics and GoPro (GPRO). GoPro is expected to release its Karma drone in time for holiday shopping.

GoPro has not announced pricing for its Karma drone, but does expect to price it competitively, Piper Jaffray analyst Erinn Murphy said in a June 14 research note. GoPro will face a lot of competition for share of wallet this holiday season from other consumer electronics products, such as‘s (AMZN) Echo smart speaker, Murphy said.

The Consumer Technology Association predicts sales of drones in the U.S. will top 2.8 million this year, a 149% increase from last year, and shipment revenues will reach $953 million, up 115% from 2015.