boneyard vs self-killer

boneyard

noun
  • A graveyard. 

  • A dumpsite for obsolete or unusable aircraft. 

  • In the game of dominoes, the pile of upside-down pieces that have yet to be used. 

self-killer

noun
  • One who kills oneself; a suicide. 

How often have the words boneyard and self-killer occurred in a corpus of books? (source: Google Ngram Viewer )