Commercial drone use is on the rise, and by recent estimates it could jump as high as 1.6 million units sold over the next four years.

That is according to the Federal Aviation Administration’s 2017-2037 Aerospace Forecast, which said the construction, industrial, and utility inspection sectors account for 26% of today’s commercial drone use, Construction Dive reports.

The FAA released its commercial drone regulations last year, and so far 44,000 units have registered. The agency has also issued more than 29,000 remote pilot certifications to date.

Though the unmanned aircrafts have become increasingly important to the industry, the new technology is presenting liability risks that insurance companies are stepping in to capitalize on. At present the construction and infrastructure sectors account for more than $45B of drones' total $127B market value, according to PricewaterhouseCoopers.