proneness vs weakness

proneness

noun
  • The quality or state of being prone, or of bending downward. 

  • The state of lying with the face down. 

  • Inclination of mind, heart, or temper; propension; disposition. 

weakness

noun
  • The condition of being weak. 

  • An inadequate quality; fault 

  • A special fondness or desire. 

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