freak accident vs probability

freak accident

noun
  • An incident, especially one that is harmful, occurring under highly unusual and unlikely circumstances. 

probability

noun
  • An event that is likely to occur. 

  • The state of being probable; likelihood. 

  • A number, between 0 and 1, expressing the precise likelihood of an event happening. 

  • The relative likelihood of an event happening. 

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