yackety-yak vs yattering

yackety-yak

noun
  • prolonged chatter; uninterrupted, idle talk; gossip 

verb
  • To talk pointlessly and uninterruptedly. 

yattering

noun
  • trivial talk; prattle 

How often have the words yackety-yak and yattering occurred in a corpus of books? (source: Google Ngram Viewer )