endurance vs unsteadiness

endurance

noun
  • The length of time that a ship's rations will supply 

  • The measure of a person's stamina or persistence. 

  • Ability to endure hardship. 

unsteadiness

noun
  • The quality of being unsteady. 

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