exoneration vs purgation

exoneration

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

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

purgation

noun
  • The process or act of cleansing from sin or guilt. 

  • The process or act of purging, such as by the use of a purgative. 

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