Year	% of total
1990	33.480003032769254
1991	33.313584391476944
1992	32.72720837537269
1993	32.550525307963234
1994	31.987102824747875
1995	31.920296189580323
1996	32.29507606581923
1997	32.508793151718066
1998	32.41961963677226
1999	32.31801274093725
2000	32.71893213575962
2001	33.278004318056006
2002	33.44102841381331
2003	34.41680023041322
2004	34.67754850109508
2005	35.04904240440362
2006	35.4888037362557
2007	35.93815273777623
2008	36.56547780395429