Year	% of total
1990	23.44436167259869
1991	20.80289660743473
1992	20.952528398641643
1993	20.68288978482645
1994	20.59770502637161
1995	19.74859767572628
1996	18.963222362986734
1997	18.909252959625316
1998	18.830369920893254
1999	18.758272388935954
2000	18.01125428693237
2001	17.41582503383344
2002	16.995073520882915
2003	15.969150942192742
2004	16.059718251565783
2005	15.90115618748206
2006	15.766799750762974
2007	15.742950524682149
2008	14.910232096523327