pita vs pitta bread

pita

noun
  • A flat bread pouch used for making sandwiches such as gyros or falafels. 

  • The plant which yields the fiber. 

  • A fiber obtained from the Agave americana and related species, used for making cordage and paper. 

pitta bread

noun
  • A flat, unleavened bread made from wheat flour; the rounds are cut in half, and may be made into pockets or used with a dip such as taramosalata, houmous or tzatziki. 

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