cask vs keg

cask

noun
  • A large barrel for the storage of liquid, especially of alcoholic drinks. 

verb
  • To put into a cask. 

keg

noun
  • A round, traditionally wooden container of lesser capacity than a barrel, often used to store beer. 

verb
  • To store in a keg. 

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