Year	% of cohort
1971	76.7365798950195
1972	79.0307312011719
1973	81.7814102172852
1974	74.0700378417969
1975	78.6371078491211
1976	77.0849227905273
1977	77.5966033935547
1978	75.5660018920898
1980	75.4680023193359
1983	81.475700378418
1984	81.3044281005859
1986	76.1005172729492
1989	67.7928924560547
1991	62.9915390014648
1993	65.7915191650391
1995	55.030158996582
2002	67.7386169433594
2007	76.92578125