Year	Percent
1990	5.48
1991	5.42
1992	5.35
1993	5.29
1994	5.22
1995	5.16
1996	5.09
1997	5.03
1998	4.96
1999	4.9
2000	4.84
2001	4.77
2002	4.71
2003	4.64
2004	4.58
2005	4.51
2006	4.45
2007	4.38
2008	4.32
2009	4.25
2010	4.19
2011	4.12
2012	4.06
2013	3.99
2014	3.93
2015	3.86