Year	Percent
1980	0.593
1981	0.596
1982	0.6
1983	0.594
1984	0.588
1985	0.586
1986	0.599
1987	0.607
1988	0.605
1989	0.603
1990	0.604
1991	0.604
1992	0.566
1993	0.587
1994	0.6
1995	0.608
1996	0.598
1997	0.594
1998	0.582
1999	0.539
2000	0.529
2001	0.526
2002	0.524
2003	0.523
2004	0.523
2005	0.523
2006	0.53
2007	0.537
2008	0.539
2009	0.548
2010	0.543
2011	0.56
2012	0.564
2013	0.57
2014	0.577
2015	0.575
2016	0.568
2017	0.556
2018	0.551
2019	0.552
2020	0.553
2021	0.554
2022	0.555
2023	0.556
2024	0.556