prove out vs validate

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. 

validate

verb
  • To have its validity successfully proven. 

  • To check or prove the validity of; verify. 

  • To render valid. 

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