Bengal gram vs chickpea

Bengal gram

noun
  • A form of chickpea, or the flour made from it 

chickpea

noun
  • A seed of this plant, often used as a food. 

  • An annual Asian plant (Cicer arietinum) in the pea family, widely cultivated for the edible seeds in its short inflated pods. 

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