Year	Percent
1973	27.12
1974	32.5
1975	43.27
1976	43.95
1977	21.81
1978	25.36
1979	33.91
1980	32.03
1981	27.9
1982	33.81
1983	41.23
1984	44.09
1985	35.58
1986	37.07
1987	9.564
1988	3.754
1990	0.5741
1991	5.842
1992	7.065
1993	5.784
1994	12.49
1995	12.49
1998	7.559
1999	7.332
2000	5.945
2001	5.829
2002	7.259
2003	5.971
2004	5.273
2005	2.804
2006	8.124
2007	9.884