„Among younger adults aged 25-34, attainment of at least upper secondary is 65.3 %, well below the OECD average of 84.6 %, which is partly due to more than 20 % (in 2015-16) of lower secondary students failing to graduate with the certificate required to access upper secondary.“
OECD (Hrsg.), „Education Outlook. Spain“ (2018), S. 11