propriety vs usage

propriety

noun
  • The fact of possessing something; ownership. 

  • Suitability, fitness; the quality of being appropriate. 

  • Correctness in behaviour and morals; good manners, seemliness. 

usage

noun
  • The act of using something; use, employment. 

  • Custom, tradition. 

  • The established custom of using language; the ways and contexts in which spoken and written words are used, especially by a certain group of people or in a certain region. 

  • A custom or established practice. 

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