Year	% of total
1970	6.712177878009255
1971	6.751301419111846
1972	6.482731509150915
1973	6.593901251070526
1974	5.409043402344724
1975	5.098107751454696
1976	4.392177753399299
1977	4.67080535496056
1978	4.500607576224999
1979	4.655339488708557
1980	5.025561216992745
1981	4.770043177950391
1982	4.7608061665013715
1983	4.695566046243884
1984	4.3327198925504185
1985	4.714784064964388
1986	4.927524474269022
1987	5.017572965727657
1988	5.478421220166222
1989	5.269523756280298
1990	9.350356740518212
1991	9.237399287989508
1992	9.961216574811186
1993	10.79646017699115
1994	11.19435874834729
1995	11.90097660685896
1996	11.595526135585482
1997	11.225188227241615
1998	11.164057181756297
1999	13.891310665504214
2000	13.749277874061235
2001	13.918439716312056
2002	14.613450659962288
2003	14.281220509594212
2004	13.699049954030034
2005	13.824451410658305
2006	13.938618925831204
2007	13.339670468948036
2008	12.536255236867547