assertion vs protestation

assertion

noun
  • A statement or declaration which lacks support or evidence. 

  • A statement in a program asserting a condition expected to be true at a particular point, used in debugging. 

  • The act of asserting; positive declaration or averment. 

  • Maintenance; vindication 

  • Something which is asserted; a declaration; a statement asserted. 

protestation

noun
  • A declaration in common-law pleading, by which the party interposes an oblique allegation or denial of some fact, protesting that it does or does not exist, and at the same time avoiding a direct affirmation or denial. 

  • a formal solemn objection or other declaration 

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