insincerity vs mendacity

insincerity

noun
  • Property of being insincere, lacking sincerity or truthfulness. 

mendacity

noun
  • The fact or condition of being untruthful; dishonesty. 

  • A deceit, falsehood, or lie. 

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