catnap vs twenty winks

catnap

noun
  • A brief, light sleep, usually during the daytime. 

verb
  • To take a catnap (short sleep or nap). 

  • To kidnap a cat. 

twenty winks

noun
  • A very short sleep, half as long as forty winks. 

How often have the words catnap and twenty winks occurred in a corpus of books? (source: Google Ngram Viewer )