Germ vs diehard

Germ

noun
  • a German person. 

diehard

noun
  • A person with such an attitude. 

adj
  • Unreasonably or stubbornly resisting change. 

  • Fanatically opposing progress or reform. 

  • Complete; having no opposite opinion of anything in a particular topic of one's values; thorough of in one's beliefs. 

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