Year	% of total
1970	72.78247569686009
1971	71.97869531505442
1972	70.45950228303866
1973	70.16967250252021
1974	69.698273598176
1975	69.4890872074339
1976	69.1014325351399
1977	68.95663682498757
1978	69.03523214379805
1979	69.5662027006734
1980	69.51746349080832
1981	69.67889014994853
1982	68.68981645166726
1983	66.84743938537801
1984	65.68747283959314
1985	61.24589637254066
1986	60.387531006450125
1987	59.33792475734754
1988	58.54696608023436
1989	57.18810960883345
1990	55.13994245357049
1991	53.586839266450916
1992	53.69536423841059
1993	53.336878489763365
1994	53.03807723467459
1995	52.01188225762895
1996	51.06901217861976
1997	49.337221633085896
1998	47.43624161073826
1999	45.35920293654955
2000	44.22680412371134
2001	43.41412012644889
2002	42.287091590787355
2003	40.97165991902834
2004	39.71459343026387
2005	39.12704598597038
2006	39.04761904761905
2007	37.4025974025974
2008	35.975471269588915