Year	% of total
1970	95.03844468761066
1971	96.88439587094638
1972	96.67635318482786
1973	96.44677041058515
1974	97.01335982512414
1975	95.56645269689392
1976	95.9193858690283
1977	95.8281354380716
1978	95.66621653732994
1979	94.93970980780753
1980	95.35437488198642
1981	95.37737999163947
1982	94.62861033354447
1983	94.52706041246644
1984	95.34513767976858
1985	95.22922298243441
1986	93.16229705932021
1987	92.31247448161834
1988	93.19830969594273
1989	93.43559706170974
1990	97.70114942528735
1991	97.74647887323944
1992	97.70114942528735
1993	97.6401179941003
1994	97.92899408284023
1995	97.61904761904762
1996	97.21362229102168
1997	97.41100323624595
1998	97.34513274336283
1999	97.3293768545994
2000	97.32620320855615
2001	97.1590909090909
2002	96.33333333333334
2003	96.61538461538461
2004	96.53179190751445
2005	96.30681818181817
2006	97.24770642201835
2007	96.74185463659147
2008	95.66666666666667