shaman vs theurgist

shaman

noun
  • A traditional (unscientific) faith healer. 

  • A member of certain tribal societies who acts as a spiritual and, or religious medium between the concrete and spirit worlds. 

theurgist

noun
  • One who claims or is alleged to perform magic with the aid of beneficent spirits. 

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