Year	% of cohort
1972	87.6559066772461
1977	87.6852569580078
1978	87.7462005615234
1979	82.5222930908203
1980	91.2231063842773
1981	90.154167175293
1982	90.3695831298828
1983	75.2600936889648
1999	90.4763565063477
2000	77.1733932495117
2008	86.6612091064453
2011	94.6162185668945