Year	Percent
1971	3.832
1972	5.851
1973	0.6248
1974	0.3481
1975	0.7873
1976	0.259
1977	1.002
1978	0.6473
1979	0.3201
1980	0.3047
1981	6.185
1982	0.6723
1983	0.875
1984	1.742
1985	1.675
1986	3.065
1987	1.693
1988	1.538
1989	3.735
1990	1.571
1991	4.958
1992	2.033
1993	2.793
1994	6.076
1995	5.507
1996	8.035
1997	4.726
1998	3.635
1999	5.36
2000	5.658
2001	4.428
2002	8.395
2003	5.654
2004	4.766
2005	3.11
2006	5.046
2007	7.46