pale rider vs quietus

pale rider

noun
  • Death, the Grim Reaper or angel of death; and one of the Four Horsemen of the Apocalypse. 

quietus

noun
  • Death. 

  • Final settlement (e.g., of a debt). 

  • A stillness or pause; something that quiets or represses; removal from activity. 

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