voodoo vs voodooism

voodoo

noun
  • Any of a group of related religious practices found chiefly in and around the Caribbean, particularly in Haiti and Louisiana. 

  • The spiritual beliefs of the Ewe/Fon of West Africa, practiced chiefly in Benin and in the south of Togo. 

  • Any sort of magical or irrational approach to a problem. 

verb
  • To bewitch someone or something using voodoo 

voodooism

noun
  • A religious cult, from Haiti, involving witchcraft and sorcery. 

  • Any voodoo practice. 

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