aggressiveness vs backbone

aggressiveness

noun
  • The state or quality of being aggressive. 

  • The propensity of a soil or water to dissolve metal or cement structures. 

  • The result or product of being aggressive. 

backbone

noun
  • Courage, fortitude, or strength. 

  • The series of vertebrae, separated by disks, that encloses and protects the spinal cord, and runs down the middle of the back in vertebrate animals. 

  • Any fundamental support, structure, or infrastructure. 

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