litany vs repetition

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. 

repetition

noun
  • The act or an instance of repeating or being repeated. 

  • The act of performing a single, controlled exercise motion. A group of repetitions is a set. 

verb
  • To petition again. 

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