skillage vs skillfulness

skillage

noun
  • The state of being highly skilled, the state of being skillful. 

  • The differentiating, or skilling, of call distribution based on an individual's skill level, expertise, or training. 

skillfulness

noun
  • The state or quality of being adept or skillful. 

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