% Chance to increase potential tier?

In the past, I would have agreed with the 10% to epic and 5% to unique estimate, but...



This seems more accurate now.
Went through my notes:
Earlier efforts, 9 items altogether ,took 9 cubes on average to get to epic
Newer efforts, 8 items, took 21 cubes on average to get to epic

So guessing 5% to epic, 2% to unique for regular cubes, down from original 10%/5%.

Huh, actually I can boast similar numbers... but I've only cubed 7 items epic total so it's not very representative (8, 12, 7, ~15, 25, 28, 13)