disheartenment vs melancholia

disheartenment

noun
  • The state of being disheartened; dejection. 

  • The act of disheartening. 

melancholia

noun
  • Deep sadness or gloom; melancholy 

  • depression, characterised by irrational fears, guilt and apathy 

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