[showerst]

I see it sort of like pot smoking. In about a two decades, we went from "probably the most dangerous drug in the United States today" (Reagan), to "I smoked but I didn't inhale" (Clinton) to "Of course I inhaled, that was the point." (Obama).

It's not that pot suddenly epically skyrocketed in the voting-age population, it's just that enough people either had smoked pot, been around those who did, or watched media that made light of it to realize it wasn't a 100% mark of evil.