let up vs recede

let up

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

  • To cease or stop. 

recede

verb
  • To move back; to retreat; to withdraw. 

  • To cede back; to grant or yield again to a former possessor. 

  • To take back. 

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