golden years vs superannuation

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. 

superannuation

noun
  • The condition or of being superannuated; old age or obsolescence. 

  • A retirement benefit fund, an accumulation of regular deductions from one′s wage or salary while employed and similar regular contributions from the employer, usually administered by an independent entity; a pension. 

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