Historical clue formulations

• "Pretty sure" — 2021-01-23
• "To the best of my knowledge" — 2019-03-05
• "Yes, that's my opinion" — 2018-02-13
• Not-so-firm affirmative — 2016-08-27
• "Yes, if you ask me" — 2011-08-09
• Tentative "yes" — 2004-12-11
• "That's my understanding" — 2003-04-18