Year	Percent
1990	0.1
1991	0.1
1992	0.1
1993	0.2
1994	0.2
1995	0.2
1996	0.3
1997	0.3
1998	0.4
1999	0.4
2000	0.5
2001	0.6
2002	0.7
2003	0.8
2004	1
2005	1.1
2006	1.3
2007	1.5
2008	1.7
2009	1.4
2010	1.4
2011	1.5