Lower grades (1 to 6) typically have fewer than 300 pupils and often operate separately from upper grades (7 to 9), although the unified peruskoulu is gradually closing the gap between these two. Compulsory education lasts until completion of nine years of basic school or until a young person turns 16, whichever comes first. Grade repetition is rare and over 99% of young Finns successfully complete nine years of basic school.