I do not know the answer to your question.
However there are in game math tools : Salary, GS and DMI. The DMI is based on salary and GS. When the GS is at 9 (the maximum) the DMI is more than 3 times higher than when the GS is at 7 on the first friday of the season (pure 7).
There is a formula about that somewhere by @joka and his tool @coachparrot.