Year	% of total
1990	62.56395629800275
1991	61.36423756876031
1992	60.75993454810235
1993	59.945114860442914
1994	59.751171605862
1995	60.31717684610882
1996	60.29327136727603
1997	60.81569584246569
1998	61.84822397468705
1999	62.56556170495024
2000	62.627948717694835
2001	61.77356053188057
2002	62.06302364534654
2003	62.16736975978635
2004	62.22775533068871
2005	62.68461028738645
2006	62.44573200465116
2007	62.95067924425784
2008	63.006403494650336