affidavit vs paper trail

affidavit

noun
  • A signed document wherein an affiant makes a sworn statement. 

paper trail

noun
  • A written record, history, or collection of evidence. 

  • Records left by a person or organization in the course of activities. 

  • Physical evidence of something that occurred in the past. 

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