cat's whiskers vs the bee's knees

cat's whiskers

noun
  • Something considered to be outstanding. 

  • Java tea (Orthosiphon aristatus) 

the bee's knees

noun
  • Something or someone excellent, surpassingly wonderful, or cool. 

  • Used other than figuratively or idiomatically: see bee, -'s, knee. Corbiculae. 

How often have the words cat's whiskers and the bee's knees occurred in a corpus of books? (source: Google Ngram Viewer )