deplete vs step up

deplete

verb
  • To empty or unload, as the vessels of the human system, by bloodletting or by medicine. 

  • To reduce by destroying or consuming the vital powers of; to exhaust, as a country of its strength or resources, a treasury of money, etc. 

step up

verb
  • To increase, augment, or advance, especially by one or more steps. 

  • To assume or take responsibility. 

How often have the words deplete and step up occurred in a corpus of books? (source: Google Ngram Viewer )