avidity vs unwillingness

avidity

noun
  • Greediness; strong appetite. 

  • The measure of the synergism of the strength of individual interactions between proteins. 

  • Eagerness; intenseness of desire. 

unwillingness

noun
  • The property of being unwilling. 

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