Year	% of total
1970	99.23093543686042
1971	99.18624373284209
1972	99.16939250851335
1973	99.15855216195868
1974	99.0746751502686
1975	99.12162389426965
1976	99.0734188657124
1977	99.09620754521778
1978	99.12184781885097
1979	99.06277352018718
1980	99.01809571512527
1981	99.02310639740686
1982	99.0379112727256
1983	98.9430680635738
1984	98.91705873451991
1985	98.90296480264917
1986	98.87366399813253
1987	98.8525920551167
1988	98.84243490540015
1989	98.78193203778444
1990	18.181818181818183
1991	21.73913043478261
1992	20.833333333333336
1993	20.833333333333336
1994	20
1995	20
1996	19.230769230769234
1997	19.230769230769234
1998	18.51851851851852
1999	17.857142857142858
2000	17.857142857142858
2001	17.24137931034483
2002	17.24137931034483
2003	16.666666666666664
2004	16.129032258064516
2005	15.625
2006	15.151515151515152
2007	15.151515151515152
2008	14.705882352941178