impotence vs impotentness

impotence

noun
  • Powerlessness; incapacity. 

  • Inability to copulate or beget children; sterility, erectile dysfunction, etc. 

impotentness

noun
  • The quality of being impotent. 

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