Like football, pop music, and democracy itself, pizza follows in the long American tradition of things that began overseas before the United States imported, violently altered, and eventually defined the institution. Although the first pizza shops didn't open in the U.S. until the early 20th century, hundreds of years after the original Neapolitan pies, we now spend $37 billion a year on pizza, accounting for a third of the global market.

The obsession deepens. On any given day, about 13 percent of Americans eat pizza, according to a new report from the Department of Agriculture. One in six guys between the ages of two and 39 ate it for breakfast, lunch, or dinner today. In part due to this obsession, per capita consumption of cheese is up 41 percent since 1995.

Drawn from the report, here are seven facts about Americans and pizza, presented free of moralizing comments about whether or not it is healthy or sensible for the American diet to consist so overwhelming of bread adorned with tomato-cheesey gloop.

- About 1 in 8 Americans eats pizza any given day. Pre-teeners eat about 2x the national average, while Americans over 60 eat about half the national average.

- More than one-quarter of boys between 6 and 19 eat pizza every day. Women eat less pizza than guys at just about every age level, but girls between 6 and 19 still eat more pizza than any other category of guys.

- Pizza-eaters get between a quarter and a third of their daily energy from pizza. Although 40- and 50-somethings aren't the most avid pizza eaters, they get the highest share of calories from them on the days when they do order or make a pie.

- In a typical pizza-eating session, an adult consumes 744 calories. A Double Quarter-Pounder with Cheese at McDonald's has 750 calories.