high point vs rooftop

high point

noun
  • The point of the highest elevation in a given area. 

  • A climax; the best time in a given period. 

rooftop

noun
  • The area atop a roof. 

  • The top layer of a roof; the material covering or composing a roof. 

How often have the words high point and rooftop occurred in a corpus of books? (source: Google Ngram Viewer )