That's the average, sure, but since Amazon allows each customer to pick a charity, I imagine some charities got a lot more, and some a lot less.
According to my account page, I've generated $100.71 for the charity I selected, and, overall, they've received $273.64 as a part of the program. So I guess the charity I selected wasn't all that popular. But I expect other, more mainstream charities, were.