Year	% of total
1990	33.6146097755559
1991	32.93978275465841
1992	32.08265437909118
1993	31.29799886937623
1994	31.131316361106208
1995	32.06277050973817
1996	31.764777984708893
1997	30.30844240100143
1998	29.764561781229574
1999	30.157550490287843
2000	29.680025330201243
2001	29.088988563084268
2002	28.006550338201947
2003	23.772493248409752
2004	23.119124945466663
2005	23.021195374676683
2006	23.531758606907214
2007	21.70274748916171
2008	24.131030498354683