Year	% of total
1990	87.35333678275428
1991	87.02482209530052
1992	86.7339860700911
1993	86.45377574011896
1994	85.78006034058163
1995	86.12003422875789
1996	86.26586863506333
1997	86.54812139539543
1998	87.2952512744649
1999	87.7881220047167
2000	88.28164065081714
2001	87.9836616610713
2002	88.45434425813761
2003	88.37490832215012
2004	88.33557108841937
2005	88.57931636397302
2006	88.02492290242452
2007	88.0304536658084
2008	87.83188318538258