Number One is a no-brainer. McDonald's clocked in with annual revenue (2012) of $34.17 billion. Yeow, that's a lot of quarter pounders with cheese. Taco Bell is 6th, Dunkin' Donuts is 7th, KFC is 9th. So, who is #2?
Answer, along with back story, and reasons why this might be important to the real estate industry, can be found here. If you want a clue, #2 has about 10,000 more stores that #1.