Year	Percent (Units)
1980	0.014
1981	0.014
1982	0.013
1983	0.011
1984	0.011
1985	0.010
1986	0.010
1987	0.010
1988	0.009
1989	0.008
1990	0.007
1991	0.008
1992	0.007
1993	0.008
1994	0.008
1995	0.008
1996	0.009
1997	0.009
1998	0.008
1999	0.008
2000	0.008
2001	0.008
2002	0.008
2003	0.007
2004	0.007
2005	0.007
2006	0.007
2007	0.007
2008	0.007
2009	0.007
2010	0.007
2011	0.007
2012	0.008
2013	0.008
2014	0.008
2015	0.008
2016	0.007
2017	0.008
2018	0.008
2019	0.008
2020	0.012
2021	0.013
2022	0.021
2023	0.026
2024	0.034
2025	0.040
2026	0.046
2027	0.054
2028	0.060
2029	0.065