ceasing vs round the clock

ceasing

noun

  • A cessation. 

round the clock

noun

  • A variant of the game of darts in which players attempt to hit each section of the dartboard sequentially, from lowest to highest number. 

prep

  • nonstop, 24 hours per day. 

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