Data from the National Center for Eduction Statistics. Table 220.40: Fall 2010 first-time kindergartners' reading, mathematics, and science scale scores, by selected child, family, and school characteristics: Fall 2010, spring 2011, spring 2012, and spring 2013 SDG indicator 4.2.1 - Proportion of children under 5 years of age who are developmentally on track in health, learning and psychosocial well-being, by sex. Source: Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011). Internet Archive URL: https://web.archive.org/web/2017*/http://nces.ed.gov/programs/digest/d15/tables/dt15_220.40.asp?current=yes