Does this metric pass the smell test?

Via Silicon Alley Insider, an analysis by a company called Drake Direct claims that 1 in 4 pageviews in the US goes to Facebook.

Hmm. I don’t doubt that Facebook gets a truly enormous amount of traffic. But 25% of the Internet? This must be some sort of derivative or artificial metric. It’s not 1 of 4 of mine. I know a handful of people that might reach that percentage — but then that number of people represents only a sample of heavily-engaged users.

Do you use Facebook that much?