inflexibility vs pliability

inflexibility

noun
  • The quality or state of being inflexible, or not capable of being bent or changed; unyielding stiffness 

pliability

noun
  • The quality or state of being pliable; flexibility; pliableness. 

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