kail vs kale

kail

noun
  • A broth made with kale or other vegetables; hence, any broth; also, a dinner. 

kale

noun
  • Broth containing kale as a chief ingredient. 

  • An edible plant, similar to cabbage, with curled leaves that do not form a dense head (Brassica oleracea var. acephala) 

  • Any of several cabbage-like food plants that are kinds of Brassica oleracea. 

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