Book of Common Prayer vs prayer book

Book of Common Prayer

name
  • The liturgy of the Church of England, first compiled by Thomas Cranmer in 1549 after the (Act of Uniformity). 

prayer book

noun
  • A book containing religious prayers 

  • The Book of Common Prayer 

  • A small holystone 

How often have the words Book of Common Prayer and prayer book occurred in a corpus of books? (source: Google Ngram Viewer )