If you’ve watched a tv show, movie or other entertainment product on demand with Comcast, you’re not alone.  The cable giant announced yesterday that it’s reached the 20 billion mark for on demand viewings since the service debuted in 2003.

The most watched movie was the comedy hit The Hangover and the most watched series is Comedy Central’s South Park, according to the Hollywood Reporter.

The number is even more impressive when you consider how quickly on demand is picking up steam.  It took until April 2009 to reach 11 billion shows or movies watched via the service.  It just two years, it’s gone up nine billion.

The cable company says it will honor some of the bigger performer in the on demand area with a the Xfinity On Demand Awards.

Other movies that make the list are The Blind Side and Couples Retreat and popular tv shows include Entourage and Sex in the City. TV series have attracted approximately 5.2 billion Comcast on demand views.

On demand options are increasing for Comcast subscribers.  The company has added series from Fox and ABC to the TV section, though the Fox shows include full ads and don’t allow viewers to fast forward.