disaccharide vs lactose

disaccharide

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

lactose

noun
  • The disaccharide sugar of milk and dairy products, C₁₂H₂₂O₁₁, a product of glucose and galactose used as a food and in medicinal compounds. 

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