Year	% of total
1970	86.51331740836304
1971	86.65186550334685
1972	86.84807995028999
1973	86.68874999274398
1974	86.41817589794111
1975	86.1465821979308
1976	86.30682270682114
1977	86.45010845122685
1978	85.85079594356174
1979	86.13818350857112
1980	86.52721396201238
1981	85.63339720252921
1982	86.25672500752873
1983	86.28507457321692
1984	87.58597966817952
1985	86.39363474644794
1986	84.69224009486311
1987	84.67984519159678
1988	82.34264051711612
1989	80.92805287819564
1990	80.8695652173913
1991	80
1992	79.7872340425532
1993	78.02197802197803
1994	74.48979591836735
1995	69.79166666666666
1996	64.8936170212766
1997	66
1998	67.0103092783505
1999	67.02127659574468
2000	65.97938144329896
2001	67.0103092783505
2002	73.25581395348837
2003	74.4186046511628
2004	72.28915662650603
2005	70.73170731707317
2006	69.87951807228916
2007	70.73170731707317
2008	69.51219512195121