proleptical vs used-to-be

proleptical

adj
  • Previous; antecedent. 

  • Anticipating the usual time; applied to a periodical disease whose paroxysms return at an earlier hour at every repetition. 

  • Of or pertaining to prolepsis; anticipative. 

used-to-be

adj
  • Former, ex-. 

How often have the words proleptical and used-to-be occurred in a corpus of books? (source: Google Ngram Viewer )