singer vs topliner

singer

noun
  • A person who, or device which, singes. 

  • A person who sings, often professionally. 

  • A machine for singeing cloth. 

  • dance figure with a fixed structure, sung by a caller, or a piece of music with that structure. 

topliner

noun
  • One who contributes to contemporary songwriting by creating vocal melodies, lyrics, or hooks related to the vocal in a song. 

  • One who is billed as the primary entertainer. 

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