However, the share of repeaters exceeds 10% in Argentina, Costa Rica, Luxembourg and Spain (Figure B1.2). See Source section at the end of this indicator for more information and Annex 3 for notes fhttn://dx.doi. The largest increase in the share of repeaters at upper secondary level is observed in the Czech Republic (10 percentage points higher than for lower secondary programmes) and Mexico (13 percentage points higher). Conversely, the share of repeaters is lower at upper than at lower secondary level in Argentina, Colombia, Costa Rica, Greece and the Slovak Republic. The number and share of over-age students are a complementary metric to those of repeaters: over-age students in the last grade are those who are likely to start the next educational level with at least a two-year delay compared to the intended age. The number of repeaters and over-age students are strictly linked, as in most countries the main reason for a high share of over-age students is the accumulation over different grades of students who have repeated at least one year (i.e. the marginal increase in the number of over-age students at each grade is correlated with the number of repeaters at that grade).