Rolls-Royce vs the bee's knees

Rolls-Royce

noun
  • Anything that is the best of its type; the best quality product possible. 

  • A car made by this manufacturer. 

name
  • any of several British companies that make motor cars, aero engines, etc. 

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 Rolls-Royce and the bee's knees occurred in a corpus of books? (source: Google Ngram Viewer )