bit part vs non-player character

bit part

noun
  • A minor role, generally not assigned a name. 

non-player character

noun
  • A character in a role-playing game or computer game whose actions are not controlled by a player. 

  • An individual who does not think for themselves nor makes their own decisions. 

How often have the words bit part and non-player character occurred in a corpus of books? (source: Google Ngram Viewer )