Year	Percent
1990	2.27
1991	2.2
1992	2.11
1993	2
1994	1.89
1995	1.81
1996	1.76
1997	1.73
1998	1.71
1999	1.71
2000	1.71
2001	1.72
2002	1.72
2003	1.71
2004	1.63
2005	1.51
2006	1.36
2007	1.19
2008	1.14
2009	1.17