DP vs cinematographer

DP

cinematographer

noun
  • A photographer who oversees the operations of the cameras and lighting when making a film. The cinematographer may also double as the camera operator of the movie camera, though this is usually done by a cameraman. The film director may also double as the cinematographer, though this is usually a different person. 

How often have the words DP and cinematographer occurred in a corpus of books? (source: Google Ngram Viewer )