Early Stats

For all of you keeping score at home; here are Addie's statistics through 5 days (percentile ranking in parenthesis).
Height - 20" (50-75%)
Weight - 7 lbs. 8 oz. (50%)
Head size - 33cm (10-25%)
We're a little concerned about the head size being below average...just kidding. But seriously, why does a baby's head size need to be tracked/ranked??? The way i see it, her neck is having a hard enough time carrying its weight as it is; so i say a statistically small head is good!