dwindle vs let up

dwindle

verb
  • To break up or disperse. 

  • To decrease, shrink, diminish, reduce in size or intensity. 

  • To lessen; to bring low. 

  • To fall away in quality; degenerate, sink. 

let up

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

  • To cease or stop. 

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