got vs ought to

got

verb
  • Expressing obligation; used with have. 

  • simple past tense of get 

  • Have, there is. 

  • Must; have/has (to). 

  • Have. 

ought to

verb
  • Indicating duty or obligation. 

  • Indicating advisability or prudence. 

  • Indicating desirability. 

  • Indicating likelihood or probability. 

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