Wait box office mojo has a ticket inflation adjustment
Rank Title (click to view) Studio Adjusted Gross Unadjusted Gross Release
1 Barbershop MGM $113,463,300 $75,782,105 9/13/02
2 Barbershop 2: Back in Business MGM $91,218,700 $65,111,277 2/6/04
3 Barbershop: The Next Cut WB $7,040,000 $7,040,000 4/15/16
So yeah it's kind of bigger than a slight decline. Perhaps a summer release would have been smarter.

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