centenarian vs septuagenarian

centenarian

adj
  • Of or relating to centenarians or a centenary celebration. 

  • Aged 100 years or more; extremely old. 

noun
  • One who or that which is at least 100 years old. 

septuagenarian

adj
  • Of or related to seventysomethings. 

noun
  • Synonym of seventysomething: a person between 70 and 79 years old. 

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