Fescennine vs X-rated

Fescennine

adj
  • Of or pertaining to the ancient Etruscan town of Fescennia 

  • obscene or scurrilous 

X-rated

adj
  • Denoting a film given an X classification. 

  • Pornographic or indecent. 

How often have the words Fescennine and X-rated occurred in a corpus of books? (source: Google Ngram Viewer )