Education is compulsory from 6 to 18 years of age for Belgians. Among OECD countries in 2002, Belgium had the third highest proportion of 18- to 21-year-olds enrolled in postsecondary education, at 42%. Though an estimated 99% of the adult population is literate, concern is rising over functional illiteracy. The Programme for International Student Assessment (PISA), coordinated by the OECD, currently ranks Belgium's education as the 19th best in the world, being significantly higher than the OECD average. Education being organized separately by each, the Flemish Community scores noticeably above the French and German-speaking Communities.