perseverate vs recur

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). 

recur

verb
  • To happen again. 

  • To recurse. 

  • To come to the mind again. 

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