Year	Percent
1990	6.1
1991	6.2
1992	6.29
1993	6.39
1994	6.49
1995	6.59
1996	6.68
1997	6.78
1998	6.88
1999	6.97
2000	7.07
2001	7.09
2002	7.11
2003	7.13
2004	7.14
2005	7.16
2006	7.15
2007	7.14
2008	7.13
2009	7.13
2010	7.12
2011	7.22
2012	7.32
2013	7.42
2014	7.52
2015	7.62