Year	Percent
1990	1.03
1991	1.33
1992	1.68
1993	2.08
1994	2.52
1995	3.01
1996	3.51
1997	3.87
1998	4.06
1999	4.17
2000	4.18
2001	4.11
2002	3.97
2003	3.88
2004	3.75
2005	3.5
2006	3.3
2007	3.16
2008	3.05
2009	2.9
2010	2.79
2011	2.6