Lower secondary school starting age (years) - BulgariaUNESCO Institute for Statistics ( UIS ). UIS.Stat Bulk Data Download Service. Accessed September 30, 2024. apiportal.uis.unesco.org/bdds.License : CC BY-4.0 LineBarMapAlso ShowNoneAggregatesSame regionSimilar valuesHighest valuesLowest valuesShareDetailsLabel