dumping ground vs garbage dump

dumping ground

noun
  • A landfill. 

  • Any place where unwanted items are sent. 

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

garbage dump

noun
  • A landfill 

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