Year	% of total
1970	55.68211045451664
1971	76.63858383181325
1972	76.37683447195927
1973	88.24243521616518
1974	90.44094348184109
1975	89.93115112443657
1976	91.02354613069356
1977	89.36221604524319
1978	88.66321811357025
1979	86.26773418065447
1980	87.64064634497561
1981	88.7683433671444
1982	87.27409229373472
1983	86.07377981719411
1984	90.30978591330854
1985	90.8517235761751
1986	87.9519019070595
1987	83.14331793433605
1988	86.62300426241391
1989	88.5439703224415
1990	88.09523809523809
1991	87.74509803921569
1992	86.93467336683418
1993	86.01036269430051
1994	85.56149732620321
1995	80.92485549132948
1996	77.63157894736842
1997	70.58823529411765
1998	60.83333333333333
1999	49.03846153846153
2000	33.33333333333333
2001	33.33333333333333
2002	31.868131868131865
2003	30.851063829787233
2004	29.292929292929294
2005	29.896907216494846
2006	28.71287128712871
2007	28.431372549019606
2008	27.358490566037734