carbohydrate vs glycogen

carbohydrate

noun
  • A sugar, starch, or cellulose that is a food source of energy for an animal or plant. 

  • Any food rich in starch or other carbohydrates. 

glycogen

noun
  • A polysaccharide that is the main form of carbohydrate storage in animals; converted to glucose as needed. 

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