ex cathedra vs ex officio

ex cathedra

prep

  • With authority based on one's rank or office. 

ex officio

adj

  • By virtue of the office that originated it, or of the title held. 

adv

  • By virtue of the office that originated it, or of the title held. 

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