miraculous vs unheard-of

miraculous

adj
  • Very surprising; amazing. 

  • By supernatural or uncommon causes, e.g. by a god; that cannot be explained in terms of normal events. 

unheard-of

adj
  • Previously unknown; unprecedented. 

  • Unknown or known to only few people. 

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