Year	% of cohort
1971	98.3918685913086
1972	98.5135879516602
1973	98.5167770385742
1974	99.0210723876953
1975	99.6065979003906
1976	99.0483627319336
1977	98.7338333129883
1978	99.0626525878906
1979	99.44287109375
1980	99.4548416137695
1981	97.6010131835938
1982	97.7516937255859
1983	97.0319595336914
1984	96.2058715820312