family unit vs inhabitation

family unit

noun
  • A unit of people consisting of family members, distant or immediate. 

inhabitation

noun
  • Population; inhabitants. 

  • The act of inhabiting, or the state of being inhabited; indwelling. 

  • Abode; place of dwelling; residence. 

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