A restaurant has 25 tables, each of which can seat up to four people. Typically, it can do three seatings per table during the dinner period from 6:00 to 10:00 p.m. The restaurant has a fairly predictable demand pattern, with Fridays and Saturdays the busiest nights and Sundays and Mondays the least busy. The restaurant is always booked to capacity on Fridays and Saturdays and sometimes on Wednesdays and Thursdays but virtually never on Sunday or Monday. It has implemented a revenue management program under which it will sometimes turn down booking requests for one or two people on Fridays and Saturdays if it believes it can fill the restaurant with bookings for larger parties of three and four people. What performance measure should it use to evaluate the effectiveness of its revenue management program?