No matter how you slice it, Americans love pizza. We eat 23 pounds of the stuff every single year. We take down 350 slices every second. Calling pizza a staple of the American diet would be a huge understatement. But pizza’s powers waft beyond the borders of the US. Our cheese-laden love affair has also extended to the rest of the world. It’s cheesy, delicious, and available just about anywhere you go. In honor of National Pizza Week, here are 20 fun facts about everyone’s favorite dinner… and lunch… and breakfast (when cold). 1. Pizza didn’t gain popularity until the 1950s, but the word “pizza” actually dates back more than a thousand years. A manuscript from 997 A.D. found in the small Italian town Gaeta, is the first known documentation of the word, Italian newspaper La Repubblica reported. 2. The first documented pizzeria in the world was opened in Port’Alba, Naples. It…