Between 1997 and 2006, the two upper secondary education options were Technical Vocational School (TEE) and the Integrated Lyceum (Eniaio Lykeio). Before 1997, four upper secondary routes existed ranging from entirely vocation to entirely academic. To this date, all available studies on vocational education refer to this earlier structures. First, Greece is one of the countries in the OECD with the lowest age of compulsory schooling.