coronet vs lieutenant junior grade

coronet

noun
  • The traditional lowest regular commissioned officer rank in the cavalry. 

  • A small crown, such as is worn by a noble. 

  • The ring of tissue between a horse's hoof and its leg. 

  • Any of several hummingbirds in the genus Boissonneaua. 

  • A species of moth, Craniophora ligustri. 

lieutenant junior grade

noun
  • A commissioned officer of the United States Navy whose rank is above an ensign's and below a lieutenant, or a corresponding rank in other navies. 

  • A commissioned officer in the United States Coast Guard, Public Health Service, or National Atmospheric and Oceanic Administration whose rank is above an ensign and below a lieutenant. 

How often have the words coronet and lieutenant junior grade occurred in a corpus of books? (source: Google Ngram Viewer )