Overpopulation plagued the box office this weekend, with no fewer than four major new releases competing for attention. So it was only fitting that a movie about overpopulation won the box office, as the sci-fi parable "Elysium" took the top spot with an estimated $30.5 million.

That wasn't quite what Sony was hoping for given the film's $115 million price tag and its pedigree, as both director Neil Blomkamp ("District 9") and star Matt Damon were expected to bring more support from film fans. But it was still just enough to edge out the new R-rated Jennifer Aniston comedy "We're the Millers," which brought in a strong $26.6 million after shooting its wad with a midweek Wednesday debut.

Also debuting on Wednesday in a failed attempt to get a jump on the overcrowded marketplace was the "Harry Potter" wannabe "Percy Jackson: Sea of Monsters," which earned an estimated $14.6 million over the weekend. That's not great, but considering this unexpected sequel got the greenlight based on the overseas performance of 2010's "Percy Jackson & the Lightning Thief," Fox certainly isn't panicking just yet.

Finally, Disney also got into the mix with "Planes," their spinoff from Pixar's "Cars" franchise. And the results were mixed for them as well. On the one hand, the $22.2 million "Planes" earned is less than a third what "Cars 2" brought in over its first weekend two years ago. But on the other hand, "Planes" was originally created as a direct-to-video release, so as long as it earns back its marketing and distribution costs, any box office money have to be seen as a bonus.

Next weekend brings no relief from overcrowding, with four more releases hitting the big screen, including "Kick-Ass 2," "Lee Daniels' The Butler" and "Jobs." For now, though, here's a look at this weekend's box office top ten, courtesy of Hollywood.com:

1. "Elysium" - $30.5m (our review)

2. "We're the Millers" - $26.6m (our review)

3. "Planes" - $22.5m (our review)

4. "Percy Jackson: Sea of Monsters" - $14.6m (our review)

5. "2 Guns" - $11.1m (our review)

6. "Smurfs 2" - $9.5m (our review)

7. "The Wolverine" - $8m (our review)

8. "The Conjuring" - $6.7m (our review)

9. "Despicable Me 2" - $5.7m (our review)

10. "Grown Ups 2" - $3.7m (our review)