NPC vs walk-on

NPC

noun
  • A person with no ability to think for themselves; a sheeple (originally referring to opponents of former US President Donald Trump). 

verb
  • To act as an NPC (“non-player character”) in a game. 

walk-on

noun
  • A student athlete who wants to try out for a college sports/athletic team without the benefit of a scholarship or having been recruited. 

  • One who arrives and boards transport (such as a train or ferry) without having booked in advance. 

  • An actor of a small (or "bit") part in a theatrical production or film, often without speaking lines. 

  • Such a part in a play or film. 

How often have the words NPC and walk-on occurred in a corpus of books? (source: Google Ngram Viewer )