amplify vs rub salt in the wound

amplify

verb
  • To render larger, more extended, or more intense. 

  • To add content that is not present in the source text to the target text, usually to improve the fluency of the translation. 

  • To increase the amplitude of something, especially of an electric current. 

  • To enlarge by addition or commenting; to treat copiously by adding particulars, illustrations, etc.; to expand. 

rub salt in the wound

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

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