Year	Percent (Units)
1980	0.001
1981	0.001
1982	0.001
1983	0.001
1984	0.001
1985	0.001
1986	0.001
1987	0.001
1988	0.001
1989	0.001
1990	0.001
1991	0.001
1992	0.001
1993	0.001
1994	0.001
1995	0.001
1996	0.002
1997	0.004
1998	0.005
1999	0.006
2000	0.012
2001	0.019
2002	0.022
2003	0.024
2004	0.030
2005	0.031
2006	0.031
2007	0.034
2008	0.039
2009	0.040
2010	0.034
2011	0.035
2012	0.038
2013	0.035
2014	0.034
2015	0.025
2016	0.021
2017	0.023
2018	0.021
2019	0.019
2020	0.019
2021	0.018
2022	0.018
2023	0.016
2024	0.016
2025	0.015
2026	0.014
2027	0.013
2028	0.013
2029	0.013