If you need further proof cannabis business is booming in North America, look no further than the latest chart from The Marijuana Business Daily that tracks the number of industry conferences over the past few years. From just one event in 2013, the number grew to over 30 in 2015.

According to columnist Becky Olson, while cannabis "lifestyle" events for general marijuana users have been around for decades, conferences bringing together professionals in the industry are a new phenomenon.

"Not only are business conferences indicative of a regulated, legitimate industry," writes Olson, "but they also offer investors a way to discover investment opportunities.

Still, in a nascent industry, it's difficult to say whether the appetite for weed-industry events will continue to grow. As Olson points out. "Some conferences have already sputtered out, and others attracted significantly fewer attendees and exhibitors than promised."

Check out the chart below, and read the MBD's full analysis here.