Year	% of total
1990	67.00123737532817
1991	66.86409256753726
1992	66.67415381264058
1993	66.71671379654323
1994	66.02985566448947
1995	65.38471571983857
1996	64.82585998438638
1997	65.32123235807202
1998	67.78017575565293
1999	70.79559499379931
2000	70.50788964266839
2001	71.30233367020651
2002	71.48318370802352
2003	69.94199638865436
2004	70.66008298361615
2005	69.94893802360842
2006	71.48727557302833
2007	72.56926994098158
2008	73.52342740466973