proclivity vs weakness

proclivity

noun
  • A predisposition or natural inclination, propensity, or a predilection; especially, a strong disposition or bent. 

weakness

noun
  • A special fondness or desire. 

  • An inadequate quality; fault 

  • The condition of being weak. 

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