GI vs digger

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. 

digger

noun
  • A tool for digging. 

  • A spade (playing card). 

  • An Australian soldier. 

  • A large piece of machinery that digs holes or trenches. 

  • One who digs. 

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