interrogative vs note of interrogation

interrogative

noun
  • A question; an interrogation. 

  • A word (pronoun, pronominal adjective, or adverb) implying interrogation, or used for asking a question: why, who, when, etc. 

adj
  • Asking or denoting a question: as, an interrogative phrase, pronoun, or point. 

  • Pertaining to inquiry; questioning 

note of interrogation

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