Year	Percent
1985	0.01
1990	1
1991	1.5
1992	1.8
1993	2
1994	2.1
1995	2.1
1996	2.1
1997	2
1998	2
1999	1.9
2000	1.8
2001	1.7
2002	1.6
2003	1.5
2004	1.5
2005	1.5
2006	1.4
2007	1.4
2008	1.3
2009	1.3
2010	1.2
2011	1.2