Year	Percent
1981	0.00982
1990	0.3
1991	0.3
1992	0.4
1993	0.6
1994	0.7
1995	0.9
1996	1
1997	1.2
1998	1.4
1999	1.6
2000	1.8
2001	2
2002	2.1
2003	2.3
2004	2.3
2005	2.4
2006	2.4
2007	2.5
2008	2.5
2009	2.3
2010	2.4
2011	2.5