Year % of cohort 1986 68.4390487670898 1987 66.8521881103516 1988 68.9721221923828 1989 55.3288116455078 1990 59.5318794250488 1991 70.2548065185547 1994 58.9797286987305 1995 69.4296035766602 1996 59.9116096496582 1997 66.2204971313477