GI vs soldier-at-arms

GI

verb

  • To clean aggressively. 

noun

  • One who is demanding and strict, in the manner of a stereotypical member of the military. 

  • A member of the U.S. military. 

soldier-at-arms

How often have the words GI and soldier-at-arms occurred in a corpus of books? (source: Google Ngram Viewer )