digger vs serviceman

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. 

serviceman

noun
  • A man who serves in the armed forces. 

  • A person, especially a man, employed in service and maintenance of equipment. 

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