duration vs immutability

duration

noun
  • An amount of time or a particular time interval. 

  • The time taken for the current situation to end, especially the current war 

  • A measure of the sensitivity of the price of a financial asset to changes in interest rates, computed for a simple bond as a weighted average of the maturities of the interest and principal payments associated with it. 

immutability

noun
  • The state or quality of being immutable; immutableness. 

  • The state of being unchangeable in the memory after creation. 

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