songstress vs topliner

songstress

noun
  • A female singer. 

  • A female songbird. 

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 songstress and topliner occurred in a corpus of books? (source: Google Ngram Viewer )