acerbate vs get someone's back up

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

get someone's back up

verb
  • To annoy or anger someone. 

  • That joke really got my boss's back up. 

How often have the words acerbate and get someone's back up occurred in a corpus of books? (source: Google Ngram Viewer )