keep on at vs lean on

keep on at

lean on

verb
  • Used other than figuratively or idiomatically: see lean, on. 

  • To put pressure on; to attempt to compel a person to do something; to exert influence on. 

  • To depend upon for support; to require assistance from. 

  • To criticize or reprimand for the purpose of changing behavior. 

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