alleviation vs placation

alleviation

noun
  • the act of alleviating; relief or mitigation. 

  • the act of reducing pain or anything else unpleasant; easement 

placation

noun
  • A process or act of placating; appeasement or an expression of appeasement. 

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