Year	Percent
1960	0.05
1961	0.06
1962	0.12
1963	0.14
1964	0.18
1965	0.19
1966	0.25
1967	0.25
1968	0.28
1969	0.43
1970	0.35
1971	0.44
1972	0.46
1973	0.53
1974	0.69
1975	0.78
1976	0.78
1977	0.95
1978	0.86
1979	0.92
1980	0.78
1981	0.83
1982	1.02
1983	0.84
1984	0.8
1985	0.86
1986	0.85
1987	0.88
1988	0.86
1989	0.96
1990	0.91
1991	0.9
1992	1.03
1993	0.99
1994	0.96
1995	0.77
1996	0.84
1997	0.79
1998	0.72
1999	0.7
2000	0.8
2001	0.77
2002	0.84
2003	0.79
2004	0.78
2005	0.94
2006	1.02
2007	0.93
2008	0.98