Year	Percent
1998	3.1
1999	3
2000	3.1
2001	3.3
2002	3.3
2003	3.5
2004	3.8
2005	3.6
2006	3.6
2007	3.5
2008	3.7
2009	3.7
2010	3.6
2011	3.8
2012	4
2013	4
2014	3.9
2015	4
2016	4.1