Year	Percent
1980	0.014
1981	0.013
1982	0.013
1983	0.015
1984	0.015
1985	0.016
1986	0.016
1987	0.016
1988	0.017
1989	0.016
1990	0.016
1991	0.017
1992	0.016
1993	0.015
1994	0.016
1995	0.015
1996	0.015
1997	0.015
1998	0.016
1999	0.015
2000	0.014
2001	0.016
2002	0.016
2003	0.018
2004	0.023
2005	0.024
2006	0.023
2007	0.022
2008	0.022
2009	0.023
2010	0.025
2011	0.024
2012	0.025
2013	0.026
2014	0.027
2015	0.026
2016	0.024
2017	0.022
2018	0.022
2019	0.023
2020	0.023
2021	0.023
2022	0.024
2023	0.024
2024	0.024