Year	Percent
1990	1.54
1991	1.49
1992	1.44
1993	1.39
1994	1.34
1995	1.29
1996	1.24
1997	1.19
1998	1.15
1999	1.1
2000	1.05
2001	1.04
2002	1.03
2003	1.02
2004	1.01
2005	1
2006	0.99
2007	0.98
2008	0.97
2009	0.96
2010	0.95
2011	0.94
2012	0.93
2013	0.92
2014	0.91
2015	0.9