Year	Percent
1979	0.03798
1990	1.3
1991	2.2
1992	3.1
1993	3.6
1994	3.8
1995	4
1996	4
1997	4
1998	4
1999	4
2000	3.9
2001	3.8
2002	3.8
2003	3.7
2004	3.7
2005	3.7
2006	3.6
2007	3.6
2008	3.6
2009	3.6
2010	3.7
2011	3.7