Year	% of total
1970	48.06673815563276
1971	47.24656809647602
1972	48.374244907249356
1973	48.20348408476498
1974	49.475629313301894
1975	49.96727386541471
1976	50.320052864167685
1977	50.656096935112856
1978	51.43069155880669
1979	51.80115513139619
1980	51.36880275687813
1981	50.910901878234405
1982	50.66971931213074
1983	51.63937818527532
1984	50.86987685794947
1985	51.849959030025715
1986	51.07503001446852
1987	51.25596528569043
1988	51.76753473947876
1989	51.915972286917686
1990	96.40718562874252
1991	96.3035019455253
1992	96.19047619047619
1993	96.09665427509294
1994	96.028880866426
1995	96.11992945326278
1996	95.97806215722122
1997	96.11992945326278
1998	96.17940199335548
1999	96.37795275590551
2000	96.03305785123966
2001	95.85406301824212
2002	96.37681159420289
2003	96.06060606060606
2004	96.51006711409396
2005	96.75
2006	96.34941329856585
2007	96.20915032679738
2008	95.95827900912647