cogitate vs surmise

cogitate

verb
  • To consider, to devise. 

  • To meditate, to ponder, to think deeply. 

surmise

verb
  • To imagine or suspect; to conjecture; to posit with contestable premises. 

noun
  • Thought, imagination, or conjecture, which may be based upon feeble or scanty evidence; suspicion; guess. 

  • Reflection; thought; posit. 

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