The only thing I can add to your comment is that it's a similar situation with alcohol. It's sold legally, people start businesses to sell it, businesses pay tax towards government programs, and some people may abuse it. The only significant difference is the medicinal properties of marijuana that that have been proven over the years that have substantial beneficial effects. This leads me to believe that there is no reason to keep it illegal, and it should instead, be embraced. As for data, well there is a lot of data, marijuana has been used over decades, and whatever negative effects it has I'm sure those have already been documented.