Year	Percent
1980	0.023
1981	0.023
1982	0.023
1983	0.022
1984	0.017
1985	0.018
1986	0.019
1987	0.018
1988	0.018
1989	0.018
1990	0.017
1991	0.017
1992	0.014
1993	0.014
1994	0.014
1995	0.013
1996	0.013
1997	0.013
1998	0.014
1999	0.014
2000	0.013
2001	0.013
2002	0.014
2003	0.014
2004	0.013
2005	0.014
2006	0.014
2007	0.013
2008	0.014
2009	0.014
2010	0.015
2011	0.014
2012	0.016
2013	0.016
2014	0.017
2015	0.017
2016	0.017
2017	0.017
2018	0.017
2019	0.018
2020	0.018
2021	0.019
2022	0.02
2023	0.021
2024	0.021