Year	Percent
1990	2.5
1991	2.3
1992	2.12
1993	1.95
1994	1.88
1995	1.82
1996	1.74
1997	1.75
1998	1.71
1999	1.72
2000	1.65
2001	1.59
2002	1.55
2003	1.56
2004	1.56
2005	1.5
2006	1.21
2007	1.12
2008	1.1
2009	0.99
2010	0.94
2011	0.96
2012	0.97
2013	0.89
2014	0.91
2015	0.83
2016	0.82
2017	0.82