hhd. vs hogshead

hhd.

hogshead

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

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

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