nonstop vs round the clock

nonstop

noun
  • A linguistic sound that is not a stop; a continuant. 

  • A convenience store in parts of Europe, open 24 hours a day. 

  • A nonstop journey, especially a nonstop flight. 

adj
  • Without stopping; without interruption or break. 

  • Describing a point mutation within a stop codon that causes the continued translation of an mRNA strand. 

adv
  • Without stopping; without interruption or break 

round the clock

prep
  • nonstop, 24 hours per day. 

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. 

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