And how can you attribute this decline to specific laws? Seems it could be a result of many things such as public education & cancer outcomes becoming obvious.
When people were told they could smoke from candy-flavored USB-charged devices they jumped back on the train. Education didn't do anything, and no facts are obvious in this new world.
It's because people in general tend to learn and retain simplified versions of things. They hear that tobacco in cigarettes causes cancer but that candy-colored USB-charged devices can come without tobacco and completely miss the fact that nicotine is also a terrible substance to get hooked on. Even amphetamines are better because at least you can stop those whenever you want and all that happens is a few days of being sleepy and then you're fine. Try to stop nicotine cold turkey and, well...