disappear vs run its course

disappear

verb
  • To go away; to become lost. 

  • To make vanish; especially, to abduct and murder surreptitiously for political reasons. 

  • To go missing; to become a missing person. 

  • To vanish. 

run its course

verb
  • To come to a natural end. 

How often have the words disappear and run its course occurred in a corpus of books? (source: Google Ngram Viewer )