let up vs shut out

let up

verb
  • To cease or stop (doing something intense). 

  • To cease or stop. 

shut out

verb
  • To prevent from scoring; to perform a shutout. 

  • To hide from sight. 

  • To refuse to be open and vulnerable toward. 

  • To prevent from entering; to block or exclude. 

How often have the words let up and shut out occurred in a corpus of books? (source: Google Ngram Viewer )