I believe the dcfs ratio is 1:10 at 2 years old. The other kids are probably above 2 so that might be why they are so much bigger. Also, alot ot the kids that can't get potty trained by 3 I believe stay in the 2 yo room until they are potty trained at daycare centers. My son goes to an inhome daycare/preschool and their ratio is 1:6, and I think it works out perfect.
I found the licensing requirements on the DCFS website, http://www.state.il.us/dcfs/docs/407.pdf. It is in section 407.190, on pg 43. It says 2 years is 1:8, and a single group may not be bigger than 16 (with 2 caregivers). Personally, that seems a little high to me. My home has 2 caregivers, one will occasionally be elsewhere so then it is 1:12, but most of the time, it is 1:6 which seems to work much better and give the children more individualized attention. The children in the home though range from 2-6, so technically, they could have way more.