dice decay probabilities

Messing around with supply dice in a game. Here are the average number of times you can expect a die of a size to last if it decays to the next smaller sizer on a 1 or a 2, then be expended after 1.

d	minimum uses	avg uses
12	6	13.03
10	5	9.23
8	4	6.12
6	3	3.71
4	2	2.00