exordium vs inauguration

exordium

noun
  • A beginning. 

  • The introduction to an essay or discourse. 

inauguration

noun
  • The formal beginning or initiation of any movement, enterprise, event etc. 

  • The act of inaugurating, or inducting into office with solemnity; investiture by appropriate ceremonies. 

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