Year	Percent
1979	0.03014
1990	2.8
1991	2.7
1992	2.6
1993	2.5
1994	2.3
1995	2.2
1996	2.1
1997	1.9
1998	1.8
1999	1.6
2000	1.5
2001	1.4
2002	1.3
2003	1.3
2004	1.2
2005	1.1
2006	1.1
2007	1
2008	1.2
2009	1.2
2010	1.1
2011	1.1