Relative chances, in the code:
MovementIncreasingEnchant 100
FeatherweightEnchant 30
StoneLegsEnchant 30
PowerslideEnchant 30
JumpIncreasingEnchant 100
DoubleJumpEnchant 60
TripleJumpEnchant 60
ElvenBootsEnchant 60
OutgoingDamageIncreasingEnchant 34
OutgoingRedFireDamageIncreasingEnchant 17 (same for the other five colors too)
ManaCostReducingEnchant 100 (this is actually mana regen now)
ShotSpeedIncreasingEnchant 100
CooldownDecreasingEnchant 100
RecoilIncreasingEnchant 30
IncomingDamageDecreasingEnchant 100
AcidGillsEnchant 30
MinorCloakOfShadowsEnchant 30 (ignore the "Minor")
RisktakerEnchant 30
You can think of the numbers as "if this entry is eligible for picking at all, this many balls with that name on it go in the bag, and one is randomly drawn from the bag after all are added".
I hope that helps