Plots body mass index (in kilograms per square meter) based on the CDC growth charts. It should be noted that these charts are prescriptive rather than descriptive; they reflect what the National Center for Health Statistics thinks the distribution of weights in American children ought to be, rather than what it is (see the original paper, 2000 CDC Growth Charts for the United States: Methods and Development, page 16). That's why we get otherwise meaningless statements about 15% of children being over the 95th percentile; the percentile lines reflect the distribution of weight from 1970.