Legal marijuana is one of the fastest-growing industries in the United States, and last year a record number of startups made deals with venture capitalists eager to get in on the ground floor.

VCs invested a total of $215.2 million across 98 deals in 2015, up from 63 deals worth $97.1 million in 2014, according to a report from venture capital researcher CB Insights.

Pot remains illegal under federal law, but 23 states and Washington, D.C. have legalized medical marijuana sales, and Alaska, Colorado, Oregon, and Washington State have legalized the drug for recreational use. The industry is on track to generate more than $6 billion in revenue this year and is expected to bring in over $21 billion a year by 2020, according to a report by big data firm New Frontier and cannabis investor network The ArcView Group.

The largest investment in 2015 was Privateer Holdings's monster $75 million round in April, from investors including Peter Thiel's Founders Fund. Privateer is a holding company that owns pot brand Marley Natural, the website Leafly, and Canadian medical marijuana producer Tilray.

The ArcView Group, which connects investors with marijuana entrepreneurs, says its network made 66 deals for a total of $45 million in 2015.