This is according to a recent Washington Post article. (link)

A recent Scripps Howard/Ohio University poll of 1,010 Americans found that 36 percent suspect the U.S. government promoted the attacks or intentionally sat on its hands. Sixteen percent believe explosives brought down the towers. Twelve percent believe a cruise missile hit the Pentagon.

I also love this quote from the article:

"It’s a much greater stretch to accept the official conspiracy story than to consider the alternatives."

Thanks to NickHaC for the link to the story. He’s just watched the Loose Change film and agrees with me that they make a pretty compelling argument that, 5 years later, there are still way too many questions unanswered.