mussitate vs yatter

mussitate

verb
  • To talk indistinctly; to mutter. 

  • To say (words, etc.) indistinctly; to mutter. 

yatter

verb
  • To natter; to prattle; to chatter mindlessly. 

noun
  • Natter; prattle; mindless chatter. 

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