Year	Percent
1971	0.8384
1972	1.159
1973	2.153
1974	2.531
1975	3.142
1976	1.969
1977	1.991
1978	2.575
1979	0.8314
1980	3.183
1981	0.08221
1982	2.726
1983	2.554
1984	1.942
1985	5.64
1986	1.844
1987	2.673
1988	3.317
1989	4.929
1990	4.962
1991	3.438
1992	2.117
1993	3.915
1994	9.749
1995	7.485
1996	2.99
1997	2.566
1998	5.727
1999	3.825
2000	3.78
2001	8.774
2002	7.968
2003	13.08
2004	7.89
2005	18.61
2006	13.04
2007	22.46