Opie & Anthony from Sirius XM Sattelite Radio had Henry Winkler on a few days ago (Fonz). He said that during Season 2; he was paid $1,000 to fly to a mall in the Midwest to sign autographs. His agent told him they were expecting "A Couple Hundred People". When he landed in the airport, he was greeted by 3,000 people. He ended up signing for several thousand people in 2 days at the mall.
He also said that during Season 3...He went to the Silverdome in Pontiac Michigan for an appearance. He thought a few hundred people would show up; but 181,000 people attended.