sugar-plum vs sweetling

sugar-plum

noun
  • Term of endearment: sweetheart, darling. 

  • A round or oval sweet/piece of candy made of boiled sugar. 

sweetling

noun
  • Darling; sometimes used as a term of endearment. 

  • A small, sweet thing. 

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