Can't you remember their attendances too, wasn't 5,000,000 screaming Geordies I know that for nowt.
Everybody had an upswing in attendances in the 90s compared to the late 70s and 80s. Look at the 20 odd thousand extra that started going to Sunderland when the SoL was built.
That coupled with a decent side is bound to be seeing a surge in attendance figures