Trade Value and Trade Income Modifiers - How do they work?

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Nov 18, 2018
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Hello everyone!

I have read through everything I could find on trading, and I think I understand how it works by now, but in my game I have noticed a discrepancy between the Trade Value that a province should provide and the Trade Value it actually provides.
In the following example you can see that the current price for fish in my game is 8.1 . The province produces 1 unit of it (since it is overseas), so far so good. Now look at the Trade Income modifiers that should apply, they should add up to +54%.

On the wiki I found a formula for Trade Value, but it does not fit with the results the game shows me. It simply says "Units produces * Price * Modifiers = Trade Value". Using this formula would give:
1*8.1*1.54 = 12.474
or if the modifiers are applied one by one: 1*8.1*1.05*1.15*1.08*1.06*1.2 =13.436

However, the Trade value that the game shows me is 8.5 . That is not even close to the value that it should be. according to this formula.
Of course, the formula could be wrong, but what else could factor into the trade value then, and is not shown ingame?

This discrepancy seems to be the case for all my provinces, I just picked this as an example. Why are my Trade Income modifiers giving so much less than what they should?

My trade efficiency is at 68%, my production efficiency is at 71%. I ran some calculations where I multiplied the price after the trade income modifiers with either of these efficiencies, but that didn't work out on most of the provinces I tested this for, so that can't be the reason.

In the forum I couldn't find anyone taking a closer look at this. So, who has any idea what invisible force is reducing the trade value this much, making my massive Trade Income Modifiers basically worthless?

The Fish example:

Another province with a different trade good for some cross checking:

I am playing unmodded EU3 Divine Wind v 5.2