PDT 2/2 : Why has tipping increased?

[Benholio]

I wasn't able to find the full list (you have to buy the guide I guess), but Zagat's most recent data indicates that west coast diners are the most stingy in the nation:

From this press release:

Tipping: Among the nation's most generous tippers are Denver (19.5%),
Detroit and Philadelphia (19.4%), all exceeding Zagat's national average of
(19%). West coast diners in San Francisco and Los Angeles are among the
least generous at 18.4%, while Honolulu averages a desultory 18% tip.