I could understand 300lbs(though it is a bit extreme) in a year. But that is with rotating the supers and having a good flow.
12fl oz/0.0295735297 L == 1 lb/0.45359237 kg
300lbs/136.077711 kg == 3600 fl oz
3600 fl oz == 28.125 gallons/106.464707 liters
But I have never had to cut out a hive that already had 500lbs of honey.