derogation vs impugnation

derogation

noun
  • An act which belittles; disparagement. 

  • The act of derogating; the temporary or partial nullification of a law. 

impugnation

noun
  • The act of impugning 

  • The act of appealing or revoking 

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