depletion vs natural wastage

depletion

noun
  • The act of depleting, or the state of being depleted; exhaustion. 

  • The consumption of a resource faster than it can be replenished. 

  • gradual expense or use of natural resources over time. 

natural wastage

noun
  • Decrease of workforce caused by non-replacement of retiring or voluntarily resigning employees and not by deliberate layoffs. 

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