annuity vs superannuation

annuity

noun
  • A right to receive amounts of money regularly over a certain fixed period, in perpetuity, or, especially, over the remaining life or lives of one or more beneficiaries. 

superannuation

noun
  • 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. 

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

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