cucumber vs zucchini

cucumber

noun
  • The edible fruit of this plant, having a green rind and crisp white flesh. 

  • A vine in the gourd family, Cucumis sativus. 

  • A person who is calm and self-possessed. 

zucchini

noun
  • The edible fruit of this variety of squash. 

  • A courgette; a variety of squash, Cucurbita pepo, which bears edible fruit. 

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