Argonaut vs mercenary

Argonaut

name
  • One of the members of the Argo who sailed with Jason in search of the Golden Fleece. 

  • A team member for the Toronto Argonauts of the Canadian Football League. 

  • Any of several ships and submarines of the British and US navies. 

mercenary

adj
  • Motivated by private gain. 

noun
  • A person employed to fight in an armed conflict who is not a member of the state or military group for which they are fighting and whose primary motivation is private gain. 

  • One hired to engage in a figurative battle, as a corporate takeover, a lawsuit, or a political campaign. 

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