aposiopesis vs litotes

aposiopesis

noun
  • An abrupt breaking-off in speech, often indicated in print using an ellipsis (…) or an em dash (—). 

litotes

noun
  • An ironic figure of speech whereby something is stated by denying its opposite, particularly the negation of a negative quality to say something positive. 

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