[miajag]

This is mostly just speculation, but I feel like there are a lot more restaurants these days than in the past, even as recently as the '80s and early '90s, when I was a kid. Big national chains like Fridays, Chili's, etc. are everywhere now. Not sure whether these are choking out local places and keeping the overall restaurant/population ratio the same, but if that ratio is indeed increasing, there is likely also a higher percentage of people who worked in a restaurant waiting/bussing tables as a job in high school/college. These people are, in my experience at least, more likely to tip more, so if there's a higher percentage of ex- and current restaurant workers eating at restaurants, that might at least partially explain the rise in average tip. Again, just a theory of mine, but I think it makes sense.