Burning Questions

I just heard on the radio that children laugh about 300 times a day on average, adults about 15. Now I am wondering does that include the number of LOL's we type or text each day??? And at what time in one's life does the 300 drop to 15? My guess is after college. Is it a gradual decrease? A sharp decline? This could be a thesis paper, just wondering what PhD I should pursue to answer these burning questions. Probably psychology... Hmmm... on second thought, no thanks. I don't want to know the specifics of how crazy I really am!