litany vs precation

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. 

precation

noun
  • A prayer or act of praying; an earnest request. 

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