Magic 2012 Draft Booster has variants:
Explore this pack in Sealed.

Sheets

Sheet basic

At rate 1/20 (5.0%)

Sheet common (color balanced)

At rate 1/101 (0.99%)

Sheet uncommon

At rate 1/60 (1.67%)

Sheet rare_mythic

At rate 2/121 (1.65%)
At rate 1/121 (0.83%)

Sheet foil

At rate 3/605 (0.5%)
At rate 1/240 (0.42%)
At rate 3/1210 (0.25%)
At rate 3/2420 (0.12%)