expressivity vs fervor

expressivity

noun
  • The quality of being expressive. 

  • The degree to which a gene affects or can affect an organism. 

fervor

noun
  • An intense, heated emotion; passion, ardor. 

  • Heat. 

  • A passionate enthusiasm for some cause. 

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