Year	Percent
1980	0.016
1981	0.016
1982	0.016
1983	0.016
1984	0.017
1985	0.018
1986	0.018
1987	0.017
1988	0.017
1989	0.015
1990	0.015
1991	0.014
1992	0.013
1993	0.011
1994	0.006
1995	0.008
1996	0.008
1997	0.009
1998	0.01
1999	0.01
2000	0.01
2001	0.011
2002	0.012
2003	0.011
2004	0.012
2005	0.012
2006	0.013
2007	0.013
2008	0.014
2009	0.015
2010	0.015
2011	0.016
2012	0.017
2013	0.017
2014	0.017
2015	0.018
2016	0.019
2017	0.019
2018	0.02
2019	0.021
2020	0.022
2021	0.023
2022	0.024
2023	0.025
2024	0.026