hogshead vs keg

hogshead

noun
  • A large barrel or cask of indefinite contents, especially one containing from 100 to 140 gallons. 

  • An English measure of capacity for liquids, containing 63 wine gallons, or about 52+¹⁄₂ imperial gallons; a half pipe. 

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 hogshead and keg occurred in a corpus of books? (source: Google Ngram Viewer )