announce vs refrain

announce

verb
  • to give public notice, especially for the first time; to make known 

  • to pronounce; to declare by judicial sentence 

refrain

noun
  • The chorus or burden of a song repeated at the end of each verse or stanza. 

  • A much repeated comment, complaint, or saying. 

verb
  • To stop oneself from some action or interference; to abstain. 

  • To abstain from (food or drink). 

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