I appreciate the reply, but it doesn't bring me much closer.

Of course I know that a starting point might be to divide the percentages equally. Obviously no-one believes they all have an equal chance. How about a next step?

How do you define your particular tiers? And where do you go from there?

I suppose in some bottom tier you might think none had a better than 5% chance. But taken with the rest of the percentages, everything must add up to 100. It's all the rest that present me with the conundrum.