happy hour vs persistence

happy hour

noun
  • A time of day, usually in the afternoon or early evening, when a bar or pub offers its drinks at a discounted price. 

  • Any small gathering, usually in the afternoon or early evening, set aside to relax and have a drink. 

  • Flowers. 

persistence

noun
  • Continuation of the previous day's weather (particularly temperature and precipitation statistics). 

  • The number of times an operation can be iteratively applied to a number before it reaches a permanently constant state. 

  • The property of being persistent. 

  • Of data, the property of continuing to exist after the termination of the program. 

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