glycogen vs polysaccharide

glycogen

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

polysaccharide

noun
  • A polymer made of many saccharide units linked by glycosidic bonds. 

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