glasses vs pair of sunglasses

glasses

noun
  • Field glasses; binoculars. 

  • Spectacles, frames bearing two lenses worn in front of the eyes. 

pair of sunglasses

noun
  • A pair of glasses with tinted lenses designed to protect the eyes from sunlight. 

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