allegation vs bum rap

allegation

noun
  • An assertion, especially an accusation, not necessarily based on facts. 

  • The act of alleging. 

bum rap

noun
  • A false accusation, or an injustice, especially one that leads to imprisonment. 

  • An undeservedly unfavorable portrayal or reputation. 

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