Year	Percent
1990	6.01
1991	6.07
1992	6.15
1993	6.26
1994	6.24
1995	6.2
1996	6.14
1997	6.11
1998	6.1
1999	6.05
2000	6
2001	5.98
2002	5.98
2003	5.95
2004	5.92
2005	5.86
2006	5.81
2007	5.78
2008	5.78
2009	6.37
2010	6.06
2011	6.06
2012	6.06
2013	6.07
2014	6.08
2015	6.08
2016	6.1
2017	6.11
2018	6.13
2019	6.15