thankfully vs unfortunately

thankfully

adv
  • In a thankful manner; giving thanks. 

  • fortunately, gratefully. 

unfortunately

adv
  • Happening through bad luck, or because of some unfortunate event. 

  • Used (as a parenthetical word) to express disappointment, compassion, sorrow, regret or grief. 

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