gab vs talk through one's hat

gab

verb
  • To talk or chatter a lot, usually on trivial subjects. 

noun
  • The mouth or gob. 

  • Idle chatter. 

  • One of the open-forked ends of rods controlling reversing in early steam engines. 

talk through one's hat

verb
  • To speak lacking expertise, authority, or knowledge; to invent or fabricate facts. 

  • To assert something as true or valid; to bluff. 

How often have the words gab and talk through one's hat occurred in a corpus of books? (source: Google Ngram Viewer )