drive home vs keep on

drive home

verb
  • To emphasize (a point) with tangible or powerful demonstration. 

  • Used other than figuratively or idiomatically: see drive, home. 

  • To push something into position completely by force. 

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 drive home and keep on occurred in a corpus of books? (source: Google Ngram Viewer )