Year	Percent
1979	0.03988
1990	1.1
1991	1.3
1992	1.5
1993	1.7
1994	1.9
1995	2.1
1996	2.3
1997	2.5
1998	2.7
1999	2.9
2000	3
2001	3.2
2002	3.3
2003	3.4
2004	3.4
2005	3.5
2006	3.5
2007	3.5
2008	3.4
2009	3.2
2010	3.2
2011	3.1