Bachelor of Science vs Master of Science

Bachelor of Science

noun
  • A three- to four-year (about 120 credit hours) undergraduate degree, with a concentration in the sciences or scientific applications. 

Master of Science

noun
  • A degree that usually requires 2-3 years beyond a Bachelor of Science and emphasizes science and scientific applications. The degree is less advanced than a Doctorate degree. 

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