Robust box office steered profit higher last quarter at Regal Entertainment, the nation’s largest exhib, as net income surged nearly ninefold to $37 million from $4 million.Revenue rose to $723 million from $614 million. In a statement, CEO Amy Miles called 2012 a record year for the Knoxville, Tenn.-based circuit. “Looking ahead, we are encouraged by the early 2013 box office results and the films scheduled for release in the coming months,” Miles said. Regal said admissions revenue rose to $485 million from $414 million. Concessions sales rose to $188.5 million from $159 million. Attendance grew to 54.8 million from 47.7 million. Average ticket prices rose to $8.86 from $8.68. Average concession spending per patron was up a dime to $3.44. Regal ended December with 540 theaters and 6,880 screens, up from 527 and 6,614 the year before.