protestation vs recommendation

protestation

noun
  • a formal solemn objection or other declaration 

  • 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. 

recommendation

noun
  • A commendation or endorsement. 

  • An act of recommending. 

  • A suggestion or proposal about the best course of action (with adpositions including "about" for the context and "to" for the course of action) 

  • That which is recommended. 

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