That is a very area specific graph. In my area, it is on the rise, regardless of what "the nation" is doing. I'm not much on stats, as I'm sure we all know where to find some that support our ideas.
My point was not the ease/difficulty issue, it was that hollywood doesn't subscribe to our idea of a good place to live. Legalizing something, and then convincing people it's bad for them is very difficult and slow going, and only works when hollywood gets behind it. They won't want to do what you suggest, and they'll quote all sorts of studies showing that there is no connection.