Year	% of cohort
1971	92.8737869262695
1972	93.0091323852539
1973	93.3952407836914
1974	94.1627426147461
1975	95.3508071899414
1976	94.3796005249023
1977	94.5795364379883
1978	94.666862487793
1979	95.4076614379883
1980	94.9181518554688
1981	93.255859375
1982	92.7199020385742
1983	92.2976913452148
1984	92.2431564331055