expunge vs extirpate

expunge

verb
  • To eliminate completely; to annihilate. 

  • To delete permanently (e-mail etc.) that was previously marked for deletion but still stored. 

  • To erase or strike out. 

extirpate

verb
  • To destroy completely; to annihilate, to cause to go extinct locally. 

  • To surgically remove. 

  • To pull up by the roots; uproot. 

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