This figure is from an earlier post about the bowl system. The reason for the expansion of the bowl system is easy: more money, for the teams and cities. As long as the fans keep coming, what's not to like?
But there must be a saturation point for any market, and maybe we've hit it for the bowl system. After 39.8% attendance this year, San Diego's Pointsettia Bowl is being discontinued - after being underperformed only by one other bowl, the Quick Lane Bowl in Detroit at 29.4%.