Year % of cohort 1977 78.3715515136719 1978 73.9359588623047 1979 73.8153610229492 1980 51.9065208435059 1981 74.3092269897461 1982 72.8628692626953 1983 73.0088806152344 1984 72.4896697998047 1985 73.1164093017578 1986 73.5195236206055 2016 99.6190185546875 2017 99.5615692138672 2018 99.3577575683594 2019 100 2020 99.6396713256836 2021 99.5809631347656