balladeer vs trouvère

balladeer

verb
  • To sing a ballad 

noun
  • A singer, particularly a professional singer who performs ballads. 

trouvère

noun
  • A medieval lyric poet using the Northern langue d’oïl (precursor dialects of modern French), as opposed to their older, southern example, the original troubadours, who used langue d’oc (Occitan) 

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