dog's bollocks vs the bee's knees

dog's bollocks

noun
  • Something that is regarded as outstanding. 

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