roll of the dice vs unpredictable

roll of the dice

noun

  • A risky or uncertain attempt to do something, especially in an unfavourable situation. 

unpredictable

noun

  • An unpredictable thing. 

adj

  • Unable to be predicted. 

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