How many official motion feature films have been produced based on Stephen King novels as of 2011?

Explanation

Stephen King is one of the biggest horror-writers ever. He was born in 1947 in Portland, Maine, and already showed promise early on. King's novels have as of 2011 been turned into 38 films, including "The Shawshank Redemption" and "The Green Mile", both of which are directed by Frank Darabont. The most famous is probably "The Shining" from 1981. Directed by Stanley Kubrick, it stars Jack Nicholson and Shelley Duvall. It is an untrue but persistent myth that King does not write autographs due to superstition. In fact, he is just against idolisation.