Year	Percent
1998	1.5
2000	3.6
2001	3.7
2002	3.6
2003	3.9
2004	3.2
2005	3.5
2006	3.1
2007	3.1
2008	3.5
2009	3.9
2010	3.5
2011	4.2
2012	4
2013	4
2014	4.4
2015	4.1
2016	4.4