dumping ground vs dumpyard

dumping ground

noun
  • A landfill. 

  • Any place where unwanted items are sent. 

  • A presumably polyphyletic supraspecific taxon where species of unclear affinities are placed. 

dumpyard

noun
  • A junkyard. 

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