golden years vs senior citizen

golden years

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

  • The period during which someone or something flourishes. 

senior citizen

noun
  • An old person, variously considered to be a person over fifty, fifty-five, sixty, or sixty-five years of age. 

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