copper vs law enforcement

copper

noun
  • A police officer. 

  • The reddish-brown colour/color of copper. 

  • A reddish-brown, malleable, ductile metallic element with high electrical and thermal conductivity, symbol Cu, and atomic number 29. 

  • Any of various lycaenid butterflies with copper-coloured upperwings, especially those of the genera Lycaena and Paralucia. 

adj
  • Made of copper. 

  • Having the reddish-brown colour/color of copper. 

verb
  • To sheathe or coat with copper. 

law enforcement

noun
  • The various government agencies, regarded collectively, involved in the prevention of crime and the apprehension of criminals. 

  • The task of ensuring obedience to the law. 

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