doubt vs insurance

doubt

verb
  • To be undecided about; to lack confidence in; to disbelieve, to question. 

noun
  • Disbelief or uncertainty (about something); (countable) a particular instance of such disbelief or uncertainty. 

insurance

noun
  • The business of providing insurance. 

  • A means of indemnity against a future occurrence of an uncertain event. 

  • The car was totalled, but fortunately I had insurance. 

  • Any attempt to forestall an unfavorable event. 

  • A bet made after the deal, which pays off if the dealer has blackjack. 

  • An insurance policy 

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