drop in the sea vs small beer

drop in the sea

noun
  • A very small or insignificant amount; something of little importance. 

small beer

noun
  • Something that is of relatively little importance. 

  • Beer with a low alcoholic content, usually between 0.5% and 2.8%. 

  • Used other than figuratively or idiomatically: see small, beer. 

How often have the words drop in the sea and small beer occurred in a corpus of books? (source: Google Ngram Viewer )