Food, laundry soap, etc. Same stuff you buy. I think we're about $420, which comes out to about $84/person. But each person isn't using $84 worth of crap.
DH is a big eater, and there has to be beer, of course. I eat an average amount and DD eats almost nothing.
But the boys! OMG! Like I said, they eat everything. If you have a big, muscular 16-18 year old playing footbal, he has to be counted as 2-3 people...that's how much he eats!
So, we're 5 people, but as far as eating goes, we're:
DH - 1.5
Me - 1
DD - .5
DS - 3
DS - 2
We're more like 8 people. In a year or two, we'll be 9.

In 5.5 years, we'll be 2.5