Pizza truly is America’s national food, statistically speaking. That’s not because one in eight people in the US over the age of two will eat pizza on any given day. It’s because, unlike other food groups, the chance an American will eat a slice doesn’t vary much by gender or race.

Today is National Pizza Day, so we took a look at data from the US Department of Agriculture (USDA). Their most recent pizza study, published in 2014, shows that 21% of white Americans aged two to 19 will eat pizza on any given day; for black and Hispanic Americans, that figure is almost identical, at 20%. Men eat more pizza than women, but not by much: 15% of men, compared with 11% of women.

The only factor which seems to affect pizza intake is age. Americans aged six to 19 are four times more likely to be found eating pizza than those over 60. The USDA also asks people to complete detailed food diaries to find out what they are eating when. Pizza for dinner is uncommon – most people eat pizza as a snack (59%) or as lunch (28%), and 2% of the country eats it as breakfast.

Many other food groups look very different in the numbers. Take soda, for example: Americans consume more cola than juice, but that varies significantly by race and income. Black and Mexican adults get 60% more of their calories from sugary drinks than white Americans.

There isn’t much historical data available on pizza consumption. So we looked for clues elsewhere. The USDA has data going back to 1909 showing how much of which cheeses have been consumed. Overall, total cheese consumption has risen remarkably, but one stands out: per capita consumption of mozzarella was seven times higher in 1994 than it was in 1970.