Year	% of total
1970	46.1044922971856
1971	47.139028247889456
1972	47.79052992597708
1973	49.13244301439871
1974	50.56643865898034
1975	50.02655667105766
1976	48.79087848506932
1977	47.164158133491526
1978	47.20761261066682
1979	47.42207751084066
1980	48.863310337669894
1981	50.23562236670206
1982	51.994156658016955
1983	52.10032416077607
1984	52.208391636860696
1985	52.13736637235312
1986	53.10793787893115
1987	52.456127802439376
1988	53.37262915154528
1989	53.504062742210834
1990	65.06973140495867
1991	63.2932661238206
1992	62.4690069163513
1993	61.648652168251076
1994	61.75511800756291
1995	61.433580054538375
1996	61.88788236838651
1997	62.303875553171515
1998	61.82110768405526
1999	61.91437802907917
2000	63.853503184713375
2001	63.907372903912695
2002	64.06463982470557
2003	63.39997203970362
2004	63.76584532117931
2005	64.4286542923434
2006	65.19052523171987
2007	66.03829160530191
2008	66.47475642161204