If the transmission system loses 5.1% of the energy produced, then you'd say the efficiency of the system is 94.9% ... that's how much of the power goes to the customers.
94.9% of 3200 MW
= 0.949 x 3.2 x 10⁹ watts
= 3,036.8 MW
= 3.0368 Gigawatts
= 3,036,800,000 watts
= 3,036,800 kilowatts