hajji vs imam

hajji

noun
  • a Muslim who has participated in a hajj. 

  • A Muslim or Arab. 

imam

noun
  • One who leads the salat prayers in a mosque. 

  • A Shi'ite Muslim leader descended from the prophet Muhammad and functioning as his spiritual successor. 

  • One of the Twelve imams, descendants of Muhammad from the seventh to ninth centuries CE who lived exemplary lives. 

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