Year	Percent
1979	3.27
1980	3.18
1981	3.2
1982	3.21
1983	4.54
1984	4.41
1985	4.21
1986	4.18
1987	3.34
1988	2.92
1989	2.74
1990	2.81
1991	4.19
1992	3.79
1993	3.36
1994	3.41
1995	3.71
1996	3.61
1997	3.91
1998	4.09
1999	3.85
2000	5.54
2001	5.31
2002	6.24
2003	6
2004	6.22
2005	5.96
2006	0.6418
2007	0.4341
2008	0.3962
2009	0.5804
2010	0.6565
2011	0.8312
2013	2.8224
2014	1.7728
2015	2.7963