Year	Percent
1979	7.9
1989	5.7
1991	5.9
1995	6.2
1997	6.2
1998	6.4
1999	6.6
2000	6.5
2001	6.2
2002	6.4
2003	6.5
2004	6.6
2005	6.9
2006	6.8
2007	7.2
2008	7.3
2009	7.6
2010	7.8
2011	7.8
2012	7.8
2013	7.7
2014	8.1
2015	8
2016	8