So I made some adjustments as you mentioned, Meni... I'm not sure that clears up any confusion, just seems to be trading it for different confusion.
So we have a 95% block, which is good luck, but a 13% block which is bad luck. Seems like we should still have some sort of positive/negative list as to if we are under or over expected shares (difficulty).
I don't think it's that important to know if it's above/below difficulty. "Luck" gives the connotation of making comparisons in the percentile space. Then average luck is 69.3% of the difficulty, which is the 50% percentile (median). Above 50% should be green, below should be red (currently it looks like the midpoint for colors is about 40%).
Anyway, I think it will look better if all numbers in the column will be in the format ##.##%, even if it has leading or trailing 0's.
The problem I have with the original method, as I stated, was that there was no upward bound on bad luck since it can't be counter balanced by good luck (which is bound to 0 or 1).
However, with the percentile, the bad luck gets compressed at the low end and again has no meaningful bound (bad luck of .46% and .11% - a huge number of shares, but a virtually meaningless difference percent wise in human terms. .46% and .11% don't express how bad that luck really is in a way that's more visceral than the straight math.)
Maybe there's no good way to express it mathematically and it just needs an arbitrary label:
0 - 20% of shares D -> Happy face with a lollipop
21% - 60% of shares D -> Happy face
61% - 100% of shares D -> Neutral face
100% - 120% of shares D -> Sad face
120% - 200% of shares D -> Crying face
>200% of shares D -> Dead stick figure
Just a thought.

Anyway - what does everyone else think? Purely mathematic numbers that have a real meaning behind them or arbitrary "general feel" description of the luck?