Hula hooping calories burned?

I'm 16, 5' 6", and between 120-130 pounds. I hula hoop with a standard (non-weighted) hula hoop for 30 minutes a day, and I've read how it tones your stomach, and I was wondering how long it would take for me to see results? Also, how many calories does it burn? (I dont eat junk food, lots of fruits, veggies, whole grains and lean protein).