Year	% of total
1990	86.2513642336397
1991	86.20450469974597
1992	86.35118821783001
1993	86.19531098286795
1994	83.12360357087229
1995	83.11391796110279
1996	82.86431357834398
1997	82.37023320742897
1998	82.29606707644233
1999	82.09271666408947
2000	81.34438414612683
2001	81.26359441722838
2002	81.42788100532479
2003	81.35180889051438
2004	81.25307448975519
2005	81.2892125832992
2006	80.7736011311913
2007	80.85975657940003
2008	80.60643559409019