Year	Percent
1971	49.77
1972	32.39
1973	15.87
1974	16.19
1975	0.9122
1976	0.7044
1977	20.25
1978	12.57
1979	9.819
1980	20.61
1981	27.14
1982	18.82
1983	15.64
1984	13.26
1985	26.19
1986	17.09
1987	16.95
1988	18.62
1989	19.96
1990	17.51
1991	18.18
1992	21.32
1993	20.37
1994	19.84
1995	15.86
1996	16.06
1997	17.21
1998	13.35
1999	16.41
2000	11.73
2001	16.21
2002	6.715
2003	14.99
2004	15.46
2005	11.11
2006	12.87
2007	18.01