Year	% of total
1990	38.881383669618764
1991	38.57070506508535
1992	38.22697305821194
1993	38.23026143415647
1994	38.56977975832861
1995	38.53880265492899
1996	38.306919558294524
1997	38.48964336166796
1998	38.936531476940154
1999	39.97687149821917
2000	40.52835875203534
2001	41.132927647314695
2002	41.450008482220824
2003	39.98647500187607
2004	41.26133692345864
2005	40.83345835735851
2006	41.73016127792527
2007	41.87633064122613
2008	41.19312012261531