chorea vs khorovod

chorea

noun
  • An Ancient Greek circular dance accompanied by a chorus. 

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

khorovod

noun
  • a Slavic art form, a combination of a circle dance and chorus singing, similar to chorea of ancient Greece, also in Romania (horă) 

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