Year	Percent
1991	3.13
1992	3.01
1993	2.22
1994	2.4
1995	2.82
1996	2.45
1997	2.09
1998	2.19
1999	2.17
2000	2.01
2001	2.09
2002	1.43
2003	1.33
2004	1.29
2005	1.27
2006	1.2
2007	1.22
2008	1.16
2011	0.99
2012	1