Year	Percent
1986	3.9
1989	4.2
1992	4.3
1996	4.3
1997	4
2000	3.6
2001	4
2002	3.7
2003	3.8
2004	3.9
2005	4.1
2006	4
2007	4.4
2008	4.6
2009	4.5
2010	4.7
2011	4.8
2012	5
2013	4.9
2014	5.1
2015	5.1
2016	4.9