inflexibility vs stringency

inflexibility

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

stringency

noun
  • A tightness or constriction. 

  • A rigorous imposition of standards. 

  • A scarcity of money or credit. 

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