Strong Box Office for Constantine reports that Constantine performed strongly with its R-rating:

Warner Bros. Pictures’ Constantine, starring Keanu Reeves and Rachel Weisz, opened close in second place with $34.6 million from 3,006 theaters. The film, based on the “Hellblazer” graphic novels, cost under $100 million to make. It marks the 5th highest non-#1 opening for a movie in box office history for the three-day frame, and is the third-best President’s Day holiday weekend opener ever, trailing just Daredevil ($45 million) and 50 First Dates ($45.1 million).

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Source: Box Office Mojo