centumvirate vs decemvirate

centumvirate

noun
  • A group of one hundred people, especially (politics) a council of about 100 men who share power or rule, particularly (historical) such a group in ancient Rome. 

decemvirate

noun
  • A group of ten people, especially (politics) a council of ten men sharing office or power and particularly (historical) the groups of ten men who reformed and codified Roman law circa 450 BCE. 

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