balladeer vs front man

balladeer

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

verb
  • To sing a ballad 

front man

noun
  • The lead singer in a musical group. 

  • A person acting as the public face of some other, covert group. 

  • striker, attacker, forward. 

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