Year	% of cohort
1970	88.4748001098633
1971	81.6790313720703
1972	79.9828414916992
1973	80.4134216308594
1974	79.9063873291016
1975	81.7573928833008
1976	84.7596130371094
1977	82.1636428833008
1978	79.1543426513672
1979	78.8280029296875
1980	79.365852355957
1981	82.2237319946289
1982	79.8666076660156
1983	85.3750381469727
1984	82.3931427001953
1985	85.5292587280273
1986	83.747802734375
1987	77.901252746582
1988	83.7054061889648
1999	92.3875732421875
2000	89.2049179077148
2001	90.6459197998047
2004	85.6548309326172
2005	89.3387908935547
2006	90.4780731201172
2007	87.9152603149414
2008	90.7098693847656
2009	94.4241180419922
2010	96.39501953125
2013	90.3412399291992