bring to an end vs keep on

bring to an end

verb
  • To cause to stop or complete. 

keep on

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

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

  • To persist or continue. 

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

How often have the words bring to an end and keep on occurred in a corpus of books? (source: Google Ngram Viewer )