exoneration vs palliation

exoneration

noun
  • The state of being disburdened or freed from a charge. 

  • An act of disburdening, discharging, or freeing morally from a charge or imputation. 

palliation

noun
  • Extenuation; mitigation. 

  • The alleviation of a disease's symptoms without a cure; temporary relief. 

How often have the words exoneration and palliation occurred in a corpus of books? (source: Google Ngram Viewer )