Year	% of cohort
1970	85.4189987182617
1971	78.9945297241211
1972	77.7230529785156
1973	77.4858093261719
1974	76.4941482543945
1975	78.655891418457
1976	82.201789855957
1977	78.9861602783203
1978	76.7244262695312
1979	75.354850769043
1980	75.933708190918
1981	80.1431427001953
1982	76.3603820800781
1983	82.8429183959961
1984	79.7243423461914
1985	83.324348449707
1986	80.8885803222656
1987	74.533332824707
1988	81.3459396362305
1999	90.5128479003906
2000	86.9948120117188
2001	89.2788619995117
2004	82.792236328125
2005	86.4375228881836
2006	88.8678131103516
2007	85.7180404663086
2008	87.9460067749023
2009	93.8219909667969
2010	95.8385391235352
2013	86.8950576782227