codex vs parchment

codex

noun
  • An early manuscript book. 

  • An official list of medicines and medicinal ingredients. 

  • A book bound in the modern manner, by joining pages, as opposed to a rolled scroll. 

parchment

noun
  • A document made on such material. 

  • The creamy to tanned color of parchment. 

  • Material, made from the polished skin of a calf, sheep, goat or other animal, used like paper for writing. 

  • The envelope of the coffee grains, inside the pulp. 

  • Stiff paper imitating that material. 

  • A diploma (traditionally written on parchment). 

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