difficulty vs facility

difficulty

noun
  • Physical danger from the environment, especially with risk of drowning 

  • An obstacle that hinders achievement of a goal. 

  • The state of being difficult, or hard to do. 

  • An objection. 

  • An awkward situation or quarrel. 

  • That which cannot be easily understood or believed. 

facility

noun
  • 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. 

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

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

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