Collateral weight

Examples:

1. Assuming there are a total of 1 BTC and 50,000 XLM in user account, and BTC/USD index price is 50,000, because the currency discount rate of 50,000 XLM is equal to 0, 1 BTC value is in 0~5,000,000 USD, the currency discount rate of 1 BTC is equal to 1. So the USD value of the account is 50,000 * 1 * 1 = 50,000 USD.
2. Assuming there is a total of 11,000,000 USDT in user account, and USDT/USD index price is 1, because the currency discount rate of 11,000,000 USDT is in 10,000,000~20,000,000 USD, the USD value of the account is 5,000,000 * 1 * 1 + 5,000,000 * 1 * 0.975 + 1,000,000 * 1 * 0.975 = 10,850,000 USD.