Year	% of total
1990	69.7076660275538
1991	68.39480220374523
1992	68.20809462537002
1993	67.11295124380074
1994	66.88589519255159
1995	66.61184327397282
1996	64.37583643102379
1997	63.70617339317149
1998	63.42204680814618
1999	63.72810039378987
2000	63.600998370998205
2001	63.73266031174953
2002	64.59492256236172
2003	65.25824020272277
2004	65.32522138676578
2005	65.69883016027754
2006	65.1114816402381
2007	64.82770633708977
2008	64.05148496412825