This is an overview of types of things Yelp Trends show- if you scroll through you come across graphs of vegetarian vs vegan in different cities across different years, and other interesting graphs. Relates to the recent threads here of vegetarian vs. vegan, how your location impacts your eating, and more.
Worth taking a look at...
http://eater.com/archives/2014/07/25/eye-opening-food-trend-charts-yelp.php