Year	% of cohort
1991	96.6389389038086
1992	95.6368789672852
1993	95.1205520629883
1994	95.2607192993164
1995	95.8949127197266
1996	95.2380905151367
1997	94.6839218139648
1998	95.6198883056641
1999	95.6950225830078
2000	96.4887771606445
2001	96.5841827392578
2002	96.4062805175781
2003	96.5842514038086
2004	96.7979888916016
2005	96.8362274169922
2006	96.5816192626953
2007	95.6020736694336
2008	95.1876373291016
2009	97.4826278686523
2010	96.2891387939453
2011	95.400032043457
2012	95.7761611938477
2013	96.1177215576172
2014	94.0056686401367
2015	96.8737411499023
2016	97.7248611450195
2017	98.4649963378906
2018	98.5826187133789
2019	98.8213882446289
2020	98.7360382080078
2021	98.9063415527344