mugger vs thief

mugger

noun
  • A person who assaults and robs others, especially in a public place. 

  • A large crocodile, Crocodylus palustris, of southwest Asia, having a very broad wrinkled snout. 

  • A person who makes exaggerated faces, as a performance; a gurner. 

thief

noun
  • One who steals another person's property, especially by stealth and without using force or violence. 

  • One who carries out a theft. 

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