keep on vs shut down

keep on

verb
  • To persist or continue. 

  • To cause or allow to remain in the on or open position. 

  • To cause or allow to remain in an existing position. 

  • To persist in talking about a subject to the annoyance of the listener. 

shut down

verb
  • To close, terminate, or end. 

  • To pass (another vehicle), especially quickly. 

  • To turn off or stop. 

  • To emotionally withdraw into oneself as a defense mechanism; to block out external stressors. 

How often have the words keep on and shut down occurred in a corpus of books? (source: Google Ngram Viewer )