Year	Percent (Units)
1980	0.886
1981	0.857
1982	0.876
1983	0.771
1984	0.777
1985	0.756
1986	0.776
1987	0.783
1988	0.798
1989	0.663
1990	0.678
1991	0.726
1992	0.693
1993	0.682
1994	0.647
1995	0.649
1996	0.623
1997	0.637
1998	0.622
1999	0.565
2000	0.559
2001	0.564
2002	0.500
2003	0.443
2004	0.498
2005	0.525
2006	0.548
2007	0.566
2008	0.579
2009	0.563
2010	0.527
2011	0.528
2012	0.540
2013	0.530
2014	0.500
2015	0.463
2016	0.374
2017	0.304
2018	0.236
2019	0.166
2020	0.120
2021	0.114
2022	0.119
2023	0.120
2024	0.121
2025	0.121