pickpocket vs sneak thief

pickpocket

noun
  • One who steals from the pocket of a passerby, usually by sleight of hand. 

verb
  • To pick pockets; to steal. 

sneak thief

noun
  • A thief who steals without being noticed and without using violence. 

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