singer vs singer-songwriter

singer

noun
  • A person who sings, often professionally. 

  • A machine for singeing cloth. 

  • A person who, or device which, singes. 

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

singer-songwriter

noun
  • A musician who both sings and composes, especially when recording or performing his/her own compositions. 

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