this brings down the average performance of the country see figure moreover the very small proportion of students who achieve the highest levels in science mathematics or reading levels or which is far below the average across oecd countries means that there is a very small pool of young schoolleavers who are well prepared to pursue higher level technical and scientific education a major challenge for a country seeking to develop its knowledgebased industries nearly one third of yearolds have repeated a year in costa rica above all oecd countries except mexico see figure however grade repetition rates in primary school almost halved between and from to as a result of new rules restricting its usage see chapter