Transformers: Dark of the Moon

This summer, it's a Tale of Two Box Offices. The best-of-times part of the scenario: Only ten movies have ever made more than a billion dollars in worldwide ticket sales, and three of those have happened this summer. First was 'Pirates of the Caribbean: On Stranger Tides,' then this past weekend, 'Harry Potter and the Deathly Hallows, Part 2,' and now, a couple days later, 'Transformers: Dark of the Moon.'

As of August 2, according to distributor Paramount, the robot threequel has scored $1.004 billion. Without adjusting for inflation, that makes it the ninth highest-grossing movie of all time. 'Harry Potter' is slightly ahead at No. 8, with $1.016 billion, and 'Pirates' is in sixth place with $1.033 billion.

So how is it possible (and this is the worst-of-times part of the scenario) that 2011's domestic box office is lagging behind 2010's by 4 percent? According to Variety, year-to-date grosses come to about $6.8 billion, nearly $300 million behind the $7.1 billion in tickets sold during the first seven months of last year. What's more, not even this August's handful of potential blockbusters (like 'Rise of the Planet of the Apes' and 'Conan the Barbarian') are expected to be enough to close the gap. How can a summer with an unprecedented number of billion-dollar movies still result in a box office slump?

Variety's analysis doesn't provide an answer, but it surely has to do with the changing habits of you, the moviegoer.