pat oneself on the back vs prate

pat oneself on the back

prate

verb
  • To talk much and to little purpose; to be loquacious; to speak foolishly. 

noun
  • Talk to little purpose; trifling talk; unmeaningful loquacity. 

How often have the words pat oneself on the back and prate occurred in a corpus of books? (source: Google Ngram Viewer )