Year	Percent
1967	26.84
1968	48.12
1969	31.01
1970	21.7
1971	14.33
1972	9.167
1973	18.76
1974	13.09
1975	5.536
1976	4.607
1977	10.14
1978	23.07
1979	25.71
1980	21.07
1981	5.193
1982	36.74
1983	30.79
1984	46.06
1985	19.64
1986	25.82
1987	29.33
1988	44.71
1989	35.8
1990	35.72
1991	42.65
1992	24.59
1993	25.19
1994	23.86
1995	25.7
1996	24.62
1997	19.42
1998	20.65
1999	20.92
2000	12.18
2001	18.46
2002	12.44
2003	14.66
2004	15.6
2005	7.689
2006	6.439
2007	22.81