It is also possible that there are aspects to this question that complicate the data on either side.

On the one side is the pro-legalization faction. They would like it known that "everybody" does it and therefore it should be legal.

On the other side is government. They would love to get their hands on the money that marijuana generates, if only they could figure out how to tax it without making it legal.

Both sides might easily exaggerate the facts.