guidon vs lieutenant junior grade

guidon

noun
  • A soldier assigned to carry such a banner. 

  • A small pennant or banner carried by infantry soldiers to direct troop movement. 

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 guidon and lieutenant junior grade occurred in a corpus of books? (source: Google Ngram Viewer )