rub salt in the wound vs twist the knife

rub salt in the wound

verb
  • To make an injury, physical or emotional, feel worse. 

twist the knife

verb
  • To deliberately do or say something to worsen a difficult situation or increase a person's distress, irritation, or anger. 

How often have the words rub salt in the wound and twist the knife occurred in a corpus of books? (source: Google Ngram Viewer )