Year	Percent
1967	36.7
1968	29.52
1969	13.78
1970	15.72
1971	8.6
1972	5.686
1973	18.1
1974	14.01
1975	30.73
1976	46.25
1977	38.71
1978	34.92
1979	30.47
1980	57.48
1981	52.32
1982	48.3
1983	56.63
1984	25.29
1985	48.15
1986	40.4
1987	31.59
1988	30.66
1989	33.18
1990	26.75
1991	33.87
1992	26.62
1993	33.93
1994	21.79
1995	6.045
1996	20.08
1997	23.11
1998	15
1999	9.603
2000	12.84
2001	11.53
2002	7.813
2003	15.38
2004	18.35
2005	9.923
2006	10.98
2007	5.133