Year	Percent
1990	1.21
1991	1.28
1992	1.4
1993	1.45
1994	1.44
1995	1.34
1996	1.33
1997	1.31
1998	1.09
1999	1.21
2000	1.16
2001	0.71
2002	0.58
2003	0.55
2004	0.53
2005	0.45
2006	0.41
2007	0.35
2008	0.32
2009	0.31
2010	0.32
2011	0.28
2012	0.27
2013	0.25
2014	0.27
2015	0.27
2016	0.26
2017	0.23