flexibility vs inflexibleness

flexibility

noun
  • The quality of being flexible; suppleness; pliability. 

  • The quality of having options. 

inflexibleness

noun
  • The quality or state of being inflexible 

  • Obstinacy of will or temper; firmness of purpose that will not yield to importunity or persuasion; unbending pertinacity. 

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