noontime vs twelve noon

noontime

noun
  • Approximately noon. 

  • Noon. 

  • The time at which something peaks in some way (e.g., in vitality, in influence, in reknown) (by analogy with the waxing of the sun each day). 

twelve noon

How often have the words noontime and twelve noon occurred in a corpus of books? (source: Google Ngram Viewer )