pencil case vs pencil pouch

pencil case

noun
  • An object purposed to contain different stationery like pencil, rubber, correction fluid, etc. 

pencil pouch

noun
  • A small bag used for holding pencils and other creative instruments, usually with a zipper to keep the items in the bag. Most commonly used by students. 

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