Year	% of total
1990	76.04954399739496
1991	75.86982378339056
1992	76.68781049964676
1993	76.64479383365713
1994	75.86304515399017
1995	74.22522504165944
1996	72.8404607578063
1997	71.12504681719346
1998	70.27469937689024
1999	68.46019863973446
2000	64.67108296823318
2001	65.2374327095462
2002	65.74558433485971
2003	64.96129560969324
2004	66.14171385387986
2005	66.24780200390386
2006	65.90754634995272
2007	64.32617231785233
2008	62.974125147279274