Year	% of total
1970	89.52046828019812
1971	89.53743543465687
1972	88.74030381301954
1973	87.40305709281236
1974	88.11091932855241
1975	88.73491440466921
1976	86.75811267441522
1977	86.50454006347925
1978	86.29100763949107
1979	85.87122350877581
1980	85.33801968135162
1981	85.22049602942583
1982	84.57726923750948
1983	84.13692325983747
1984	84.37750020590225
1985	84.07274142016719
1986	83.37313585173088
1987	83.06068687726918
1988	82.68510160046397
1989	82.42270560295543
1990	90
1991	88.9423076923077
1992	88.78504672897196
1993	88.47926267281106
1994	88.0184331797235
1995	87.33031674208145
1996	89.63963963963964
1997	92.27467811158799
1998	93.72384937238493
1999	95.78059071729957
2000	97.90794979079497
2001	97.62845849802372
2002	97.22222222222221
2003	97.06959706959707
2004	96.84210526315789
2005	96.79715302491103
2006	96.91780821917808
2007	96.84542586750788
2008	96.55172413793103