disaccharide vs glycogen

disaccharide

noun
  • Any sugar, such as sucrose, maltose and lactose, consisting of two monosaccharides combined together. 

glycogen

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

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