Year	Percent
1992	7.83
1993	8.38
1994	7.46
1995	7.69
1996	7.88
1997	7
1998	6.25
1999	5.18
2000	6.64
2001	7.06
2002	7.15
2003	6.99
2004	7.15
2005	7.03
2006	6.24
2007	5.97
2008	5.86
2009	5.75
2010	5.59
2011	5.25
2012	4.96
2013	4.71
2014	4.47
2015	4.2
2016	3.83
2017	3.77