dispiriting vs sustaining

dispiriting

adj
  • Lowering the morale of; making despondent or depressive; disheartening. 

sustaining

noun
  • The process by which something is sustained or upheld. 

adj
  • That sustains, supports or provides sustenance. 

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