bell pepper vs green pepper

bell pepper

noun
  • Capsicum annuum, an edible spicy-sweet fruit, originating in the New World. 

green pepper

noun
  • The green, unripe, form of the sweet bell pepper. Popular in cooking, especially Italian cuisine. The unripe bell pepper is green and generally changes to other colors as it matures, cultivars exist for red, orange, yellow and other shades. 

  • A green variety of dried peppercorn, made from the unripe berries by treating them in a manner that retains the green colour. 

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