In fact, a microwave oven may use more power when turned off than when cooking
Standby power (on average according to Korean report): 2.77W
Operating power (my microwave): 1100W
Standby: 2.77 x 24 x 356 = 23KWh
Using the microwave on average for 3.6 minutes per day: 1100 x 0.06 x 356 = 23KWh
It's not a stretch that someone uses their microwave on average less than four minutes a day.