mussitate vs natter

mussitate

verb
  • To talk indistinctly; to mutter. 

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

natter

verb
  • To talk casually; to discuss unimportant matters. 

  • To nag. 

noun
  • Mindless and irrelevant chatter. 

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