Year	% of total
1990	81.30611130885997
1991	81.0424177398029
1992	80.75528586192544
1993	80.5516819339846
1994	80.36231204146122
1995	79.78413551776556
1996	79.43362690355482
1997	79.02006462272765
1998	78.65327578497512
1999	78.34256417947087
2000	77.8252642604044
2001	77.39889955675012
2002	76.78642426725357
2003	76.57362859373833
2004	76.24617663727497
2005	76.21545308384903
2006	76.0541153881141
2007	75.90322995016496
2008	75.78740701178772