cat's meow vs greatest thing since sliced bread

cat's meow

noun
  • A highly sought-after and fancy example of something. 

greatest thing since sliced bread

noun
  • Something amazing, outstanding or praiseworthy, especially a relatively recent invention likely to improve people's lives. 

How often have the words cat's meow and greatest thing since sliced bread occurred in a corpus of books? (source: Google Ngram Viewer )