Year	% of total
1970	81.19443160126237
1971	86.57810523257339
1972	84.35397958603971
1973	87.00427664676289
1974	85.78426742664924
1975	84.47647726351623
1976	82.74485641025643
1977	86.58133614834172
1978	83.83450835038958
1979	83.01801511710674
1980	82.13487462696807
1981	83.57798072089393
1982	82.82996583656282
1983	82.84514438213515
1984	86.69253819959835
1985	85.47302700899128
1986	84.81118075406712
1987	81.76955076732821
1988	85.10134467225193
1989	85.07144457178579
1990	95.8603210363278
1991	95.67552289429055
1992	95.59556786703601
1993	95.36777091521617
1994	95.35899535899536
1995	95.09803921568627
1996	94.9216639654241
1997	94.70729751403368
1998	94.57343412526998
1999	94.53376205787781
2000	94.72750316856781
2001	94.58153141694225
2002	94.50990223113563
2003	94.86184060287736
2004	94.74761255115962
2005	94.5796968305007
2006	94.61384375695526
2007	94.76130122517955
2008	94.47465738525125