Year	Percent
1982	0.01097
1990	2.3
1991	3.2
1992	4.4
1993	6.1
1994	8.1
1995	10.6
1996	13.3
1997	16
1998	18.5
1999	20.6
2000	22.3
2001	23.6
2002	24.5
2003	25.1
2004	25.5
2005	25.6
2006	25.7
2007	25.8
2008	25.9
2009	25.8
2010	25.9
2011	26