Year	Percent
1980	0.024
1981	0.024
1982	0.024
1983	0.024
1984	0.024
1985	0.024
1986	0.023
1987	0.023
1988	0.027
1989	0.031
1990	0.03
1991	0.03
1992	0.028
1993	0.027
1994	0.025
1995	0.025
1996	0.025
1997	0.024
1998	0.024
1999	0.023
2000	0.023
2001	0.024
2002	0.024
2003	0.023
2004	0.023
2005	0.024
2006	0.024
2007	0.022
2008	0.023
2009	0.025
2010	0.026
2011	0.025
2012	0.026
2013	0.026
2014	0.026
2015	0.026
2016	0.025
2017	0.023
2018	0.022
2019	0.023
2020	0.022
2021	0.022
2022	0.021
2023	0.021
2024	0.021