doubtfully vs incontrovertibly

doubtfully

adv
  • In a doubtful manner, in context of doubt or ambiguity, questionably. 

incontrovertibly

adv
  • In an incontrovertible manner; in a manner not capable of being denied, challenged, or disputed. 

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