At what percentage do shows start to be concerned? Percentages don't matter so much as the Average Ticket Price. Any show can have a bad week, percentage-wise (during the winter, in the fall, etc.), but if the ATP is high, it says that there's still a great demand for the show.
(ex. SPRING AWAKENING just barely met its break-even point this week, but the ATP was about $70, a more-than-fair amount)
On the other hand, if CRY-BABY (this is last week's data) pulled in about 85% capacity, but had an ATP of $26... something's wrong.
"Y'know, I think Bertolt Brecht was rolling in his grave."
-Nellie McKay on the 2006 Broadway production of The Threepenny Opera, in which she played Polly Peachum