Year	Percent
1980	0.016
1981	0.016
1982	0.015
1983	0.014
1984	0.013
1985	0.012
1986	0.011
1987	0.01
1988	0.011
1989	0.011
1990	0.01
1991	0.008
1992	0.008
1993	0.007
1994	0.007
1995	0.007
1996	0.008
1997	0.008
1998	0.008
1999	0.008
2000	0.007
2001	0.007
2002	0.008
2003	0.008
2004	0.008
2005	0.008
2006	0.008
2007	0.008
2008	0.008
2009	0.008
2010	0.008
2011	0.008
2012	0.008
2013	0.008
2014	0.008
2015	0.007
2016	0.007
2017	0.007
2018	0.007
2019	0.007
2020	0.006
2021	0.006
2022	0.006
2023	0.006
2024	0.006