re-enforce vs throw back

re-enforce

verb
  • To enforce again; to re-emphasize. 

throw back

verb
  • To retort. 

  • Used other than figuratively or idiomatically: see throw, back. 

  • To revert to an earlier stage of development. 

  • To hinder the development of something. 

How often have the words re-enforce and throw back occurred in a corpus of books? (source: Google Ngram Viewer )