anonym vs code name

anonym

noun
  • An assumed or false name; a pseudonym. 

  • An anonymous person. 

  • A mere name; a name resting upon no diagnosis or other recognized basis. 

code name

noun
  • A name used to clandestinely identify somebody or something, either for military or espionage purposes, or for commercial confidentiality. 

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