prove out vs substantiate

prove out

verb
  • To demonstrate the feasibility of; to show or be shown to be feasible, accurate, true, satisfactory, as expected, hoped, stated, etc. 

  • To turn out to be feasible, accurate, true, satisfactory, as expected, hoped, stated, etc. 

substantiate

verb
  • To verify something by supplying evidence; to authenticate or corroborate 

  • To give material form or substance to something; to embody; to record in documents 

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