Correct. The sum of all assets and liabilities in the world in some unit of account (like the USD) is 0. So if we say that the average liabilities per person i

Correct. The sum of all assets and liabilities in the world in some unit of account (like the USD) is 0. So if we say that the average liabilities per person in the world is X, it turns out that the average assets per person in the world is also X.