discontinue vs persist

discontinue

verb
  • To interrupt the continuance of; to put an end to, especially as regards commercial productions; to stop producing, making, or supplying. 

  • To consciously cease the ingestion or administration of (a pharmaceutical drug). 

persist

verb
  • To cause to persist; make permanent. 

  • To go on stubbornly or resolutely. 

  • To repeat an utterance. 

  • To continue to exist. 

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