add insult to injury vs pour oil on troubled waters

add insult to injury

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

pour oil on troubled waters

verb
  • To calm, appease or quieten a person or situation. 

How often have the words add insult to injury and pour oil on troubled waters occurred in a corpus of books? (source: Google Ngram Viewer )