kibitzer vs viewer

kibitzer

noun
  • A person who offers unsolicited views, advice, or criticism; one who kibitzes. 

viewer

noun
  • Someone who views a spectacle; an onlooker or spectator. 

  • The manager of a colliery, who directs its workings and ventilation. 

  • Someone who watches television. 

  • Any optical device used to view photographic slides. 

  • A program that displays the contents of a file. 

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