impropriety vs inexpedience

impropriety

noun
  • The condition of being improper. 

  • An improper act. 

  • Improper language. 

inexpedience

noun
  • The quality or state of being inexpedient; unsuitableness or impropriety. 

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