Year	% of total
1970	94.61676693883892
1971	92.852519752402
1972	93.67100070282035
1973	93.8927924707115
1974	93.87801334596284
1975	94.1417327478126
1976	93.84240592281802
1977	93.98149834461344
1978	93.54998260617089
1979	93.92561826387312
1980	94.55996006480338
1981	92.92440471293988
1982	92.93904769720507
1983	92.56970399376485
1984	91.16275620637835
1985	90.31470208352327
1986	89.30903677240866
1987	90.7659137565207
1988	88.24540143231673
1989	88.79968908260294
1990	87.93388429752066
1991	86.58536585365853
1992	85.61151079136691
1993	84.44444444444444
1994	84.50704225352112
1995	85.59870550161813
1996	86.13138686131386
1997	85.06787330316742
1998	83.17307692307693
1999	82.42811501597444
2000	81.13821138211382
2001	83.77997179125529
2002	83.75706214689266
2003	69.00269541778977
2004	71.28463476070529
2005	74.5575221238938
2006	78.58439201451905
2007	73.63834422657952
2008	85.87699316628702