acerbate vs rile up

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

rile up

verb
  • To rile; to aggravate. 

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