Year	Percent
1997	7.1
1998	6.7
1999	6.7
2000	8.1
2001	7.6
2002	7.2
2003	7.3
2004	7.9
2005	7.7
2006	7.8
2007	7.9
2008	8.5
2009	8.7
2010	9.1
2011	9.3
2012	9.5
2013	9.5
2014	9.7
2015	9.8
2016	9.7