millet vs sorghum

millet

noun
  • Any of a group of various types of grass or its grains used as food, widely cultivated in the developing world. 

  • A semi-autonomous confessional community under the Ottoman Empire, especially a non-Muslim one. 

  • Common millet, in particular Panicum miliaceum. 

sorghum

noun
  • A cereal, Sorghum genus and species, the grains of which are cultivated to make flour and feed cattle. Almost all cultivated ones as well as some wild ones belong to the species Sorghum bicolor (syn. Sorghum vulgare). 

  • Sorghum syrup. 

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