Year	% of cohort
1971	99.1674194335938
1972	97.570182800293
1973	96.6178894042969
1974	98.5665817260742
1975	99.5411224365234
1976	99.7527923583984
1977	99.3844909667969
1978	98.0459823608398
1979	99.6800918579102
1980	99.2479019165039
1981	98.4283981323242
1982	98.8323669433594
1983	98.7813873291016
1987	99.0834274291992
1988	99.4768371582031
1989	99.8290481567383
1990	99.8221969604492
1991	99.9243087768555
1999	98.1150665283203
2000	99.704948425293
2001	98.8117065429688
2002	98.5779418945312
2003	99.0406875610352
2004	98.8966903686523
2005	99.3611526489258
2006	99.1665420532227
2007	99.7233734130859
2008	99.2806396484375
2009	99.5656127929688
2010	95.5663375854492
2012	99.9121704101562
2013	99.7051010131836
2018	99.7436981201172
2019	99.8347015380859
2020	99.697883605957
2021	99.9085388183594