my bad I misunderstood the situation.
I'm not sure I've ever found myself looking for the answer. I guess I would never know because a lot of different gear pieces provide different output gains. Weapons and trinkets are really strong pieces compared to wrists for instance.
Comparing two sims should give you two figures that you can divide for an approximate answer of the % of output gained.
Why would you be interested in this figure ? That's the real question ^^