BOB vs chorea

BOB

noun
  • Vibrator (device designed to stimulate a woman's genitals). 

adj
  • Back-of-the-book; denoting those stamps in a catalogue that are not used for the payment of regular postage fees, and are displayed separately in the catalogue after that listing; the division between these two groups varies with the publisher. 

chorea

noun
  • Any of the various diseases of the nervous system characterized by involuntary muscular movements of the face and extremities; St. Vitus's dance. 

  • An Ancient Greek circular dance accompanied by a chorus. 

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