drugget vs sheepskin

drugget

noun
  • An inexpensive coarse woolen cloth, used mainly for clothing. 

  • A floor covering made of drugget. 

sheepskin

noun
  • The tanned skin of a sheep with the fleece left on, especially when used for clothing, rugs, etc. 

  • A diploma. 

  • The skin of a sheep, especially when used to make parchment or in bookbinding. 

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