du'a' vs litany

du'a'

noun
  • private prayer by an individual 

litany

noun
  • A ritual liturgical prayer in which a series of prayers recited by a leader are alternated with responses from the congregation. 

  • A prolonged or tedious list. 

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