add fuel to the fire vs put salt on the wound

add fuel to the fire

verb
  • To worsen a conflict between people; to inflame an already tense situation. 

  • Used other than figuratively or idiomatically: see add, fuel, fire. 

put salt on the wound

How often have the words add fuel to the fire and put salt on the wound occurred in a corpus of books? (source: Google Ngram Viewer )