Year	Percent
1990	8.3
1991	8.1
1992	7.89
1993	7.69
1994	7.48
1995	7.28
1996	7.07
1997	6.86
1998	6.66
1999	6.45
2000	6.25
2001	6.42
2002	6.59
2003	6.77
2004	6.94
2005	7.11
2006	7.18
2007	7.24
2008	7.3
2009	7.37
2010	7.43
2011	7.5
2012	7.56
2013	7.63
2014	7.69
2015	7.75