Year	% of total
1990	69.56704573727691
1991	68.29141044375497
1992	68.13069536191122
1993	67.04487517626119
1994	66.85827928327772
1995	66.52155954465964
1996	64.29022395309696
1997	63.62021589694293
1998	63.33073123132915
1999	63.610543871227
2000	63.47647299144419
2001	63.59641560309525
2002	64.44475919553227
2003	65.10078546192075
2004	65.15347851462991
2005	65.50326883550204
2006	64.92560949101781
2007	64.64159207033336
2008	63.878880137293606