Last year I found a source that put it at 40% of the total. I think BroJoeK is the one who initially linked to it, and I found that further down past the point he wanted us to read.
It was an article that focused mainly on New Orleans and how New York had secured virtually every cotton contract that came available.
If you want me to find it, I'll start looking for it, but i'm not going to be in a hurry.
So out of that 40%, which shows the South was making most of the profits by the way, how much would you deduct for the cost of:
Shipping
Warehousing
Insurance
Losses not covered by insurance
Sales commissions for brokers contracting with foreign buyers
Interests to pay investors
All of which would have to be paid by Southern interests instead of Northern ones if New York were cut out of the deal.
Your memory is faulty, though 40% could easily be the combined values of shipping, warehousing, commissions, insurance, interest on debts, luxury imports plus a few wild nights on the town in the Big Apple.
Indeed, that last may be, all by itself, a reason why Charleston SC was never destined to match New York as a favorite of mariners.
Regardless, your repeated claim that all or most of Southern cotton shipped through New York is simply bogus, it didn't.
Half shipped from New Orleans and much of the rest from other Southern ports.
As for New York somehow "tying up" cotton contracts, you have no idea how much cotton was owned by residents of which cities or states or foreign countries.
That's pure speculation.