crooner vs front man

crooner

noun
  • One who croons; a singer, usually male, especially of popular music. 

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 crooner and front man occurred in a corpus of books? (source: Google Ngram Viewer )