CC vs closed captioning

CC

noun
  • companion of the Order of Canada 

closed captioning

noun
  • The display of text on a television or video screen, usually a transcription of the audio portion of a program as it occurs (either verbatim or in edited form), most frequently used by the deaf and language learners. Closed captions are encoded invisibly, and displayed by a decoder. 

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