coffee break vs happy hour

coffee break

noun
  • A rest period during the business day (usually of about 10 or 15 minutes). So named because it is an opportunity to get coffee. 

happy hour

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

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

  • Flowers. 

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