For many years attendance was free so it is unlikely they really kept a true count. It was obvious the stadium would not be full so there was really no need to keep exact records. Estiamtes from the skybox would have been sufficient probably. I think we had a couple awful weather spring games which made attendance drop way down as well. One year it was cancelled altogether because of severe rainstorms. I also think once or twice it would have been a poor crowd because of the way the game had been turned into a lowly and not very serious 'practice'. Not sure which coach did this. I never really felt Callahan and Pelini took it serious enough, disrespecting the fans somewhat and making a big joke of fans coming to watch a practice. Frankly, the game always had a decent crowd as long as I can remember but was until the past decade or so always much more of a game like scrimmage.