Actually they don’t, only 97.6% by those stats and the Pens aren’t far behind at 93.2%.
And before you start whining that the steeler’s have this huge stadium they fill and the pens this little arena to fill just remember that basic supply and demand would tend to dictate that if the Pens played fewer games the demand would tend to go up as the supply of tickets would go down, just as if the Steeler’s played more games the supply of tickets would go up and the demand would go down.