Year	Percent
1989	1.72
1990	1.69
1991	1.57
1992	1.61
1993	1.61
1994	1.62
1995	1.66
1996	1.63
1997	1.19
1998	0.64
1999	0.85
2000	0.72
2001	0.68
2002	0.55
2003	0.42
2004	0.51
2005	0.62
2006	0.6
2007	0.66
2008	0.59
2009	0.67
2010	0.62
2011	0.58
2012	0.59
2013	0.57
2014	0.59
2015	0.56
2016	0.58
2017	0.49