boiled sweet vs hard candy

boiled sweet

noun
  • A hard sweet, made by boiling sugar, which gradually dissolves when sucked. 

hard candy

noun
  • A candy prepared from one or more syrups boiled to a temperature of 160°C (320°F), thereafter becoming stiff and brittle at room temperature. 

How often have the words boiled sweet and hard candy occurred in a corpus of books? (source: Google Ngram Viewer )