Year	Percent (Units)
1980	0.013
1981	0.013
1982	0.013
1983	0.012
1984	0.013
1985	0.012
1986	0.012
1987	0.011
1988	0.011
1989	0.012
1990	0.012
1991	0.012
1992	0.011
1993	0.011
1994	0.011
1995	0.011
1996	0.011
1997	0.011
1998	0.010
1999	0.011
2000	0.010
2001	0.010
2002	0.010
2003	0.010
2004	0.010
2005	0.009
2006	0.009
2007	0.009
2008	0.008
2009	0.008
2010	0.008
2011	0.008
2012	0.008
2013	0.008
2014	0.009
2015	0.010
2016	0.009
2017	0.010
2018	0.010
2019	0.009
2020	0.008
2021	0.007
2022	0.008
2023	0.009
2024	0.009
2025	0.009
2026	0.009
2027	0.009
2028	0.009
2029	0.009