filch vs petty theft

filch

noun
  • An act of filching; larceny, theft. 

  • Something which has been filched or stolen. 

verb
  • To illegally take possession of (something, especially items of low value); to pilfer, to steal. 

petty theft

noun
  • A theft of property having a value lower than a certain small amount set forth in a statute, and considered to be a less serious class of crime. 

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