How does childhood obesity break down by age (who is most at risk)?

Generally, older children (school age and teens) are at greatest risk for becoming obese. According to the latest National Health and Nutrition Examination Survey (NHANES:2007-2008) the prevalence of obesity among US children and adolescence is as follows:

When we compare these rates to childhood obesity rates in 1980 we can see that the rates of pediatric obesity has tripled in the last 30 years.
AGE 2007-2008 1980
All (2-19 year olds) 16.9% obese not available
2-5 year olds 10.4% obese not available
6-11 year olds 19.6% obese 6.5% obese
12-19 year olds 18.1% obese 5.9% obese