horde vs viewership

horde

noun
  • A large number of people or things. 

  • A wandering troop or gang; especially, a clan or tribe of a nomadic people (originally Tatars) migrating from place to place for the sake of pasturage, plunder, etc.; a predatory multitude. 

verb
  • to travel en masse, to flock 

viewership

noun
  • collectively, the viewers of a television program or other video broadcast 

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