Maybe. It'd be interesting to do the math. If you had a 10k wealth province, 5% more would be 500 per turn, though really less after administrative costs. Hard to know without seeing the rest of the empire. I think it would be difficult, though.
I can't do all the math right now since I'm at work, and don't have access to the basic numbers (if someone could post the basic building stats for each Market upgrade level that would be awesome.)
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