Emergency department visit rates in the U.S. in 2021, by age

Visit rates are not the same as percentage of population since one patient may have had more than one visit to the ED that year. As is the case of infants where multiple infants had more than one visits to the ED in 2021.
The source adds the following information: "Data are based on a sample of 16,207 emergency department visits made by patients in 2021, representing about 140 million emergency department visits. Visit rates are based on the July 1, 2021, set of estimates of the U.S. civilian noninstitutionalized population developed by the U.S. Census Bureau. During 2021, about 4% of children had two or more ED visits in the past 12 months."