Year	Percent
1971	0.9452
1972	1.203
1973	5.417
1974	4.934
1975	10.93
1976	9.389
1977	0.826
1978	3.508
1979	5.343
1980	2.829
1981	1.004
1982	2.15
1983	5.975
1984	2.356
1985	1.682
1986	2.399
1987	1.538
1988	4.017
1989	1.088
1990	1.67
1991	0.9248
1992	5.314
1993	7.106
1994	7.958
1995	7.1
1996	6.373
1997	6.858
1998	6.32
1999	9.778
2000	10.98
2001	12.35
2002	12.29
2003	10.88
2004	10.01
2005	8.715
2006	11.09
2007	8.547