Year	Percent
1992	5.53
1993	5.46
1994	4.82
1995	4.58
1996	4.73
1997	4.14
1998	3.42
1999	2.98
2000	3.38
2001	4.17
2002	4.48
2003	3.92
2004	3.89
2005	3.82
2006	3.16
2007	2.79
2008	2.7
2009	2.5
2010	2.5
2011	2.51
2012	2.37
2013	2.17
2014	1.98
2015	1.94
2016	1.68
2017	1.67