Here are some guesstimates on %:

Salmon X Normal = 50% Salmons / 50% Normals

Salmon X Salmon = 50% Salmons / 25% Poss Supers / 25% Normals

Super X Normal = 100% Salmons

Super X Salmon = 100% Salmons / 50% Poss Supers

Super X Super = 100% Poss Supers