building vs weakening

building

noun
  • The act or process by which something is built; construction. 

  • A closed structure with walls and a roof. 

weakening

noun
  • A structural principle of mathematical logic that states that the hypotheses of any derived fact may be freely extended with additional assumptions. 

  • An instance or process of loss of strength. 

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