These were the odds, before the update:
The blue as common colour adds are mentioned first (left) and pink as common colour is last (right)
Pink Easter Box
Chirpy Boy & Bart Junior 2% 5% (Cant be awarded before 12 boxes, guaranteed at 80 boxes)
Blocko Store 3% 5% (Cant be awarded before 12 boxes, guaranteed at 81 boxes)
Easter Fence x3 20% 20%
Beach Towel & Umbrella 15% 12.5%
Easter Tree 15% 12.5%
Gold Eggs x100 0% 45%
Gold Eggs x300 45% 0%
Blue Easter Box
The Egg Council Guy 5% 2% (Cant be awarded before 12 boxes, guaranteed at 81 boxes)
Johnny Fiestas 5% 3% (Cant be awarded before 12 boxes, guaranteed at 80 boxes)
Easter Pond 12.5% 15%
Easter Egg Pile 12.5% 15%
Easter Fence x3 20% 20%
Gold Eggs x100 45% 0%
Gold Eggs x300 0% 45%
Yellow Easter Box
Sharry Bobbins 2% chance (Cant be awarded before 20 boxes, guaranteed at 80 boxes.
Hugs Bunny 3% (Guaranteed at 81 boxes)
Father Sean 5% (Guaranteed at 50 boxes)
Bunny #24601 12% (Guaranteed at 20 boxes)
Banana Dictatorship 16% (Guaranteed at 15 boxes)
Easter Gate 17%
Kodos Topiary 7%
Kang Topiary 7%
Pastel Picket Fence 31%