sheepfold vs stockyard

sheepfold

noun
  • An enclosure for keeping sheep. 

  • A flock of sheep. 

stockyard

noun
  • An enclosed yard, with pens, sheds etc. or stables, where livestock is kept temporarily before being slaughtered, treated, sold, or shipped etc. 

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