Year	% of total
1970	73.75829293613954
1971	73.25358056038922
1972	73.33034202475811
1973	73.69488211803713
1974	71.77427514313953
1975	72.76570105189408
1976	72.91721160876658
1977	73.93741542304288
1978	72.41637540265803
1979	73.09092145677928
1980	74.59369238601029
1981	73.14792860142796
1982	74.20712769356385
1983	73.32943167646535
1984	72.72330791862089
1985	71.56217318908175
1986	71.60024426281312
1987	72.14880108340637
1988	71.43502378678778
1989	72.51122599704578
1990	90.22346368715084
1991	89.67391304347827
1992	88.8586956521739
1993	87.96791443850267
1994	87.0026525198939
1995	86.3517060367454
1996	86.88118811881188
1997	86.61800486618006
1998	89.587852494577
1999	85.43689320388349
2000	87.1578947368421
2001	84.04761904761905
2002	82.9326923076923
2003	83.92070484581498
2004	81.86274509803921
2005	84.81262327416174
2006	83.87096774193549
2007	82.4524312896406
2008	82.00836820083683