old hat vs vicissitude

old hat

adj
  • Very familiar; common, hackneyed or out of date. 

vicissitude

noun
  • Regular change or succession from one thing to another, or one part of a cycle to the next; alternation; mutual succession; interchange. 

  • A change, especially in one's life or fortunes. 

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