instability vs zoanthropy

instability

noun
  • The quality of being unstable. 

  • A state that is not in equilibrium, or in which a small change has a large irreversible effect. 

zoanthropy

noun
  • A kind of delusion in which the patient believes himself transformed into one of the lower animals. 

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