Almost all 4-year-olds are enrolled in early childhood education (98% in 2011, above the OECD average of 82%). A one-year pre-school class (for 6-year-olds) aims to ensure a smooth transition from pre-primary to primary education and prepare children forthe educational programme at school. Denmark has comprehensive education from ages 6-7 until age 16, including one year of pre-school class, nine years of primary and lower secondary education integrated within a single structure, and a voluntary tenth year.