I just completed a game in which I kept track of virtually every result of anything I attempted that was labelled as "likely", "maybe", and so on (I probably missed recording a few, but I'm pretty sure not many). I figured that there might be other people who would be interested in the odds, so I am posting them now.
Code:
[B]Impossible:[/B] N/A% (didn't try any; presumably zero chance)
[B]Very Unlikely:[/B] 2.08% (1 for 48)
[B]Unlikely:[/B] 22.41% (13 for 58)
[B]Maybe:[/B] 44.57% (119 for 267)
[B]Likely:[/B] 66.67% (86 for 129)
[B]Very Likely:[/B] 97.90% (326 for 333)
Disclaimer: It's possible that there could be hidden in-game factors that determine what "likely" and so forth mean, so perhaps these numbers are only valid if you play the game similarly to the way that I do. But they remained pretty consistent throughout the game:
"Unlikely" was about 25% for most of the time, till a bad streak around 1790 or so brought it down to about 20%, after which it started recovering.
"Maybe" seemed like about 35% for the first hundred years or so, but soon thereafter got up to about 45% and stayed there.
"Very Unlikely", of course, was zero for a long time, then I got one
and it shot up, then slowly decreased.
"Likely" and "Very Likely" were very consistent.
I regret not trying a single "Impossible".