add insult to injury vs twist the knife

add insult to injury

verb
  • To further a loss with mockery or indignity; to worsen an already unfavourable situation. 

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 add insult to injury and twist the knife occurred in a corpus of books? (source: Google Ngram Viewer )