enervation vs listlessness

enervation

noun
  • State of being enervated; debility. 

  • Act of enervating; debilitation. 

listlessness

noun
  • The state of being listless; apathetic indifference; lethargy. 

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