Year	% of cohort
1971	96.7713088989258
1972	96.739013671875
1973	96.8191223144531
1974	97.3466720581055
1975	98.0462112426758
1976	97.3433609008789
1977	97.23583984375
1978	97.4134979248047
1979	97.9072723388672
1980	97.6358032226562
1981	95.9415435791016
1982	95.6642608642578
1983	95.0670471191406
1984	94.4514694213867