hussar vs zipperhead

hussar

noun
  • A member of the light cavalry of any of several European armies. 

  • A member of the national cavalry of Hungary, Croatia and Poland. 

zipperhead

noun
  • A soldier in the Royal Canadian Armoured Corps or in the Armoured Crewman military trade. 

  • A person of East Asian descent. 

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