SOS vs word to the wise

SOS

noun
  • A children's game in which players take turns to place S's and O's on a grid, collecting points by creating an "SOS" sequence. 

  • The conventional Morse code call made by a ship in distress. 

word to the wise

noun
  • A brief piece of advice. 

adv
  • Used to emphasis following as a piece of significant advice. 

How often have the words SOS and word to the wise occurred in a corpus of books? (source: Google Ngram Viewer )