Thanks in large part to sales of premium-priced tickets for 3D screenings, the box office has set a summertime record, Daily Variety reported Tuesday. Through Sunday revenue for the summer had reached $4.17 billion, versus $4.16 billion for summer 2007, the previous record, the trade publication observed. Next weekend -- the Labor Day holiday -- is expected to add about $100 million more to the total, putting the summer tally 3 percent ahead of 2007. Total admissions, however, are reportedly down about 4 percent.