entreaty vs litany

entreaty

noun
  • The act of entreating or beseeching; a strong petition; pressing solicitation; begging. 

litany

noun
  • A prolonged or tedious list. 

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

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