Year	% of total
1990	26.311611977112566
1991	27.053594979137316
1992	26.622939292969626
1993	27.536743494919662
1994	27.554906840292492
1995	27.717367298108154
1996	27.93926445284468
1997	27.713820720206105
1998	27.589633519402625
1999	27.04471284347812
2000	27.518257171616654
2001	27.65409587682799
2002	27.760166463750128
2003	28.298717266532215
2004	28.590734578771915
2005	28.799010232852535
2006	28.887569929191145
2007	29.007147675077224
2008	29.46211470836112