I haven't  seen any statistics yet but I would be really surprised if people began using marijuana simply because it was legal. I think it's similar to how some people don't drink even though it's legal. It's a personal choice and with any drug, whether it's weed, booze, or coffee, people do it for different reasons. I would say there is a much larger social impact by criminalizing it too. It pushes it to the black market and that's where you mostly find robberies, killing, and additional drugs. I respect your right to have an opinion and to not partake in any drugs you don't choose to, but I think your looking at this the wrong way. criminalizing or making things illegal doesn't prevent people from doing them, it raises the stakes and it involves those individuals already involved in criminal activities.