keep on vs ump

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. 

ump

verb
  • To act as an umpire (in). 

noun
  • An umpire. 

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