around-the-clock vs perpetual

around-the-clock

adj
  • All day and night; all of the time. 

perpetual

adj
  • Lasting forever, or for an indefinitely long time. 

  • Set up to be in effect or have tenure for an unlimited duration. 

  • Continuing; uninterrupted. 

  • Flowering throughout the growing season. 

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