According to the Centers for Disease Control and Prevention 17.7 percent of American public schools only about 18 percent of public schools study from the Centers for Disease Control and Prevention 2015 CDC study US Department of Health CDC MMWR 2015 CDC study recommends https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6430a1.htm recommends Source CDC report CDC reported – See Full Report – only about 18 percent of public schools レポート https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6430a1.htm 2015 CDC study recent CDC analysis recommends https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6430a1.htm Centers for Disease Control and Prevention