IOU vs bad news

IOU

phrase
  • I owe you. 

noun
  • An informal promissory note that is not a negotiable instrument. 

bad news

noun
  • An irritating, troublesome or harmful person, situation or thing. 

  • News of unpleasant, unfortunate or sad events. 

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