Hell, I will swag a guess: 18,000 lbs. But I could be wrong by plus or minus 7000 lbs based on the trailer's extras, like a tongue wheel, aluminum or galvanized metal used, the number and size of the bunks, single or double axle, etc.
But otherwise, you can take it to the bank.
If I sought an accurate number, I would take it over a truck scale and get an accurate reading.