constancy vs infrequency

constancy

noun
  • The quality of being constant; steadiness or faithfulness in action, affections, purpose, etc. 

  • An unchanging quality or characteristic of a person or thing. 

infrequency

noun
  • The state of being unfrequented; isolation; seclusion. 

  • The characteristic of being infrequent. 

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