Year	Percent
1990	2.02
1991	2.06
1992	2.09
1993	2.12
1994	2.15
1995	2.19
1996	2.22
1997	2.25
1998	2.29
1999	2.32
2000	2.35
2001	2.38
2002	2.41
2003	2.45
2004	2.48
2005	2.51
2006	2.54
2007	2.58
2008	2.61
2009	2.64
2010	2.67
2011	2.67
2012	2.67
2013	2.67
2014	2.67
2015	2.67