deplete vs expend

deplete

verb
  • 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. 

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

expend

verb
  • to consume, exhaust (some resource) 

  • to spend, disburse 

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