I bet there's a world wide natural experiment going on right now (since the late 90's) on that very subject. I also bet that there's several very smart people w

I bet there's a world wide natural experiment going on right now (since the late 90's) on that very subject. I also bet that there's several very smart people working on that very question. The real questions are who are these people, what is their data, and what can they conclude? Maybe the fine folks over at Freakonomics might have a hint. In the end, I believe we should believe what the academic Economists have to say about it.