Year	% of cohort
1981	88.9481964111328
1982	87.8607864379883
1984	81.2930603027344
1985	89.3352432250977
1986	86.5168609619141
1987	90.9894332885742
1988	97.1101684570312
1991	89.2438430786133
1992	98.5536499023438
1993	98.3137969970703
1994	98.2859115600586
1995	91.147346496582
1997	97.0604629516602
1998	98.6255874633789
1999	95.6272430419922
2000	98.0515899658203
2001	98.6700210571289
2003	99.1484222412109
2004	98.3633499145508
2011	97.9494018554688
2015	98.6984786987305
2016	97.3277587890625
2017	97.8553314208984
2018	97.4652709960938