Forget percentages.
According to the Times article In My Life needs to take in 320k per week to make expenses. This figure, supplied by the show, seems low because of the complex set and light plot, but let's accept it as the amount. Then there is the grey area above that mark when variables like royalties are figured and then comes profit.
The figure that you want to see is $320,000.
Since no one is chomping at the bit to get into the Music Box this moment, they may last until New Year's depending on how much money Mister Angel wants to flush down the john.
One of two things will happen. The money will dry up or the stop clause will be invoked.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher