Over-age attendance as a result of grade repetition and/or late entry risks reducing participation in education (UNESCO, 2016(7]). For all other countries with available data, this share ranges between 0% and 5% (Figure Bl.a). In the last grade of lower secondary education, this share increases for most countries and doubles on average across the OECD (from 2% to 4%). The share of over-age students increases most from the last grade of primary education to the last grade of lower secondary education for Argentina (by 10 percentage points), Costa Rica (by 14 percentage points), Luxembourg (by 12 percentage points) and Spain (by 8 percentage points), while it decreases substantially for Hungary (by 7 percentage points), highlighting a high rate of dropout and a drop in enrolment rates for 15-19 year-olds.