cocaine vs rocks

cocaine

noun
  • Any derivative of cocaine. 

  • An addictive drug derived from coca (Erythroxylum) or prepared synthetically, used sometimes medicinally as a local anesthetic and, often illegally, as a stimulant. 

rocks

noun
  • Crack cocaine. 

  • Money. 

  • Testicles. 

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