STing vs agon

STing

noun
  • Storytelling in the context of a tabletop role-playing game, especially one published by White Wolf. 

agon

noun
  • A contest in ancient Greece, as in athletics or music, in which prizes were awarded. 

  • A two-player board game played on a hexagonally-tiled board, popular in Victorian times. 

  • A struggle or contest; conflict; especially between the protagonist and antagonist in a literary work. 

  • An intellectual conflict or apparent competition of ideas. 

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