Year	Percent
1992	6.57
1993	6.79
1994	6.01
1995	6
1996	6.15
1997	5.41
1998	4.69
1999	3.98
2000	4.85
2001	5.48
2002	5.7
2003	5.32
2004	5.37
2005	5.25
2006	4.54
2007	4.22
2008	4.12
2009	3.96
2010	3.88
2011	3.72
2012	3.52
2013	3.3
2014	3.09
2015	2.96
2016	2.64
2017	2.61