Year	% of cohort
1981	86.9673309326172
1982	83.1574325561523
1985	87.2044219970703
1986	82.1641616821289
1987	90.7656326293945
1991	81.1673965454102
1992	92.455436706543
1993	89.2584609985352
1994	90.8667297363281
1995	81.2940216064453
1997	87.1845474243164
1998	92.4641265869141
1999	90.3406066894531
2000	92.3395309448242
2001	98.1335525512695
2003	98.6703796386719
2004	98.2132568359375
2011	97.8074264526367
2015	98.589599609375
2016	96.5696182250977
2017	97.2360992431641
2018	96.7772903442383