Year	% of total
1970	57.80654208543016
1971	58.59821424546635
1972	58.9500076526106
1973	58.93754322703655
1974	59.02676447020065
1975	59.245984590442546
1976	58.92179281771245
1977	58.72350267320496
1978	59.34282988665214
1979	59.56011742154064
1980	59.62001381719142
1981	59.38428590865315
1982	59.336072048749955
1983	59.61938388774377
1984	59.912063318496344
1985	59.72526116672623
1986	59.217234689677056
1987	59.30047619118762
1988	54.61093878511507
1989	51.85011599892437
1990	77.5330396475771
1991	76.78571428571429
1992	78.94736842105263
1993	77.5609756097561
1994	72.57142857142857
1995	68.42105263157895
1996	63.41463414634146
1997	58.75
1998	58.44155844155844
1999	57.333333333333336
2000	52.083333333333336
2001	50.70422535211267
2002	52.112676056338024
2003	51.09489051094891
2004	51.449275362318836
2005	53.03030303030303
2006	53.07692307692308
2007	53.125
2008	53.17460317460318