facility vs usableness

facility

noun
  • The physical means or contrivances to make something (especially a public service) possible; the required equipment, infrastructure, location etc. 

  • The fact of being easy, or easily done; absence of difficulty, simplicity. 

  • Dexterity of speech or action; skill, talent. 

  • An institution specially designed for a specific purpose, such as incarceration, military use, or scientific experimentation. 

  • A toilet. 

  • A condition of mental weakness less than idiocy, but enough to make a person easily persuaded to do something against their better interest. 

usableness

noun
  • The quality of being usable. 

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