I want to know how many discrete restaurants there are in the United
States, and how many there were every year or so for the past 20
years.
Also, I want to know how many chain restaurants there are in the
United States, and again how many there were every year or so for the
past 20 years.

McDonalds and other "joints" (burgers, tacos, a deli or sandwich
place) don't count.  Diners count.

Specifically, I'm trying to find proof for my (admittedly) casual
assertion that while there are more physical restaurants in this
country, probably on par with population growth and in line with the
decline of the home-cooked meal, that there are in fact fewer distinct
restaurants out there.  If you count all the Bennigans as one
restaurant, all the Applebees as another single restaurant, I believe
there are fewer today than 5 or 10 or 15 years ago.