perdure vs perseverate

perdure

verb
  • To continue to exist, last or endure, especially for a great length of time. 

  • To exist in such a way as to possess distinct temporal parts (in perdurantism). 

perseverate

verb
  • To persist in doing something; to continue to repeat an action after the original stimulus has ended. 

  • To cause the perseveration of (a given reflex or response). 

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