Year	% of cohort
1971	98.2437591552734
1972	96.7648468017578
1973	96.547981262207
1974	97.5661697387695
1975	99.1237030029297
1976	99.4519195556641
1978	99.0996017456055
1979	99.2734603881836
1980	98.9508590698242
1981	98.23193359375
1982	98.3727264404297
1983	98.6732406616211
1987	99.3661880493164
1988	99.5664825439453
1989	99.7141799926758
1990	99.6336212158203
1991	99.723518371582
1999	98.4331970214844
2000	99.3010101318359
2001	98.7892303466797
2002	98.9978790283203
2003	99.0243301391602
2004	99.0913314819336
2005	98.9618682861328
2006	99.4050216674805
2007	99.7287216186523
2008	99.0403213500977
2009	99.5294189453125
2010	96.5446929931641
2012	99.7461929321289
2013	99.6089019775391
2017	99.7208099365234
2018	99.8022537231445
2019	99.7829666137695
2020	99.8449630737305
2021	99.8336563110352