Year	% of total
1990	30.691442717244808
1991	29.854170396258247
1992	29.718392408585988
1993	29.456254553877585
1994	29.257261651705544
1995	30.26613737812114
1996	31.923558261767962
1997	33.05014333244688
1998	33.77683325523029
1999	34.70570095178821
2000	35.649239342309414
2001	37.52770092043291
2002	37.263040764975216
2003	37.98170932880833
2004	38.66497053331044
2005	38.31638696085641
2006	37.925212389702324
2007	37.83034723523671
2008	37.48534353706062