Year	Percent (Units)
1980	0.791
1981	0.773
1982	0.774
1983	0.759
1984	0.744
1985	0.730
1986	0.719
1987	0.709
1988	0.710
1989	0.709
1990	0.702
1991	0.698
1992	0.638
1993	0.620
1994	0.622
1995	0.614
1996	0.599
1997	0.597
1998	0.593
1999	0.593
2000	0.587
2001	0.579
2002	0.573
2003	0.556
2004	0.547
2005	0.535
2006	0.521
2007	0.513
2008	0.501
2009	0.493
2010	0.482
2011	0.472
2012	0.465
2013	0.460
2014	0.458
2015	0.464
2016	0.473
2017	0.469
2018	0.461
2019	0.459
2020	0.448
2021	0.450
2022	0.448
2023	0.441
2024	0.433
2025	0.424
2026	0.416
2027	0.409
2028	0.402
2029	0.395