beat down vs keep under

beat down

verb
  • To wear (someone) out by repeated actions that overwhelm one's patience or strength. 

  • (of rain) To strike with great force. 

  • (of the sun) To shine brightly and radiate with intense heat. 

  • Used other than figuratively or idiomatically: see beat, down. 

  • To forcefully diminish the power or influence of; to quell; to squash. 

  • To haggle with (someone) to sell at a lower price. 

  • To severely beat someone up. 

keep under

verb
  • To hold in subjection; hence, to oppress. 

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