announce vs proclaim

announce

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

  • to pronounce; to declare by judicial sentence 

proclaim

verb
  • To announce or declare. 

  • To make [something] the subject of an official proclamation bringing it within the scope of emergency powers 

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