depress vs keep under

depress

verb
  • To bring down or humble; to abase (pride, etc.). 

  • To cause a depression or a decrease in parts of the economy. 

  • To make depressed, sad or bored. 

  • To press down. 

  • To reduce (an equation) in a lower degree. 

keep under

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

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