The typical American buys precisely one book a year.
Of course, this isn't true, because when it comes to books, there is no typical American. There are a lot of Americans who buy zero books for pleasure each year. And then there are people like me who buy 400. The average is irrelevant.
When you can't figure out the best way to treat all your customers, the best way to price things, the best thing to offer, realize that the problem is almost always this: you're trying to treat everyone the same. Don't. Break them into groups with similar attributes, and suddenly the path becomes a lot more clear.