breakfast cereal vs common barley

breakfast cereal

noun
  • A food made from processed grains, such as maize, oats, wheat or rice, usually eaten for breakfast with milk and sometimes sugar. 

common barley

noun
  • A plant of the species Hordeum vulgare, which yields the commercially important cereal grain barley. 

How often have the words breakfast cereal and common barley occurred in a corpus of books? (source: Google Ngram Viewer )