Year	% of cohort
1970	85.810417175293
1971	76.592399597168
1972	75.8303833007812
1973	73.6542816162109
1974	76.5674209594727
1975	72.2933120727539
1976	79.1820678710938
1977	76.0744018554688
1978	71.9463500976562
1979	70.1281967163086
1980	70.1482772827148
1981	75.9724502563477
1982	72.5309829711914
1983	79.8755798339844
1984	76.6010971069336
1985	79.8675231933594
1986	78.7531661987305
1987	69.8258285522461
1988	76.2695465087891
1999	89.8092422485352
2000	85.4597320556641
2001	86.8435211181641
2004	82.1003112792969
2005	84.1094284057617
2006	87.6315765380859
2007	84.7335662841797
2008	85.7815093994141
2009	93.6841888427734
2010	91.9861526489258
2013	85.0870513916016