Year	% of total
1990	35.508892637107515
1991	35.32069029707244
1992	35.16665918368187
1993	34.69154042952621
1994	34.03388471125596
1995	33.964286712752035
1996	34.09438143061584
1997	34.07069874055047
1998	33.84226256528819
1999	33.223434563400275
2000	32.89287997854448
2001	32.6280756641506
2002	32.177902660154714
2003	32.96737236644899
2004	32.402710214747955
2005	32.78585802912213
2006	32.56332280119576
2007	32.716809081116395
2008	33.82053894119116