dihydrogen monoxide vs freshwater

dihydrogen monoxide

noun

  • H₂O, water. 

freshwater

noun

  • A body of fresh water 

adj

  • Consisting of fresh water. 

  • neoclassical, in reference to U.S. macroeconomics and economics departments near the Great Lakes. 

  • Unskilled as a seaman. 

  • Living in fresh water. 

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