golden years vs heyday

golden years

noun
  • The period during which someone or something flourishes. 

  • Old age; especially, the leisure years in later life after one has retired from employment. 

heyday

noun
  • A period of success, popularity, or power; prime. 

intj
  • A lively greeting. 

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