I can tell you that for natives of the South and Western USA ( not the transplants from big cities ), almost every home has at least one firearm, usually three or four ( handgun, .22, centerfire, and shotgun) . When you get to those who hunt and shoot for a little recreation, I would say most have 6 to 10. When you get to serious shooters and hunters, most have between 20 and 50. When you get to collectors, I know a dozen who have over 200, especially if they are into one make or model ( 200 Colt 1911 variants, 200 leverguns, 200 military rifles, 200 Mannlichers, etc). Out in the rural areas, 99% of homes have a half dozen firearms; ownership is almost universal.
Big cities are different, more like London or Paris, filled with people afraid of their own shadow. Every chance I get, with one of them visiting, I feed their natural curiosity and inclination to like firearms by taking them out to shoot a mix and win them over.