Year	Percent
1980	0.64
1981	0.629
1982	0.639
1983	0.641
1984	0.616
1985	0.608
1986	0.601
1987	0.588
1988	0.568
1989	0.57
1990	0.571
1991	0.577
1992	0.529
1993	0.522
1994	0.519
1995	0.514
1996	0.507
1997	0.497
1998	0.501
1999	0.502
2000	0.495
2001	0.489
2002	0.483
2003	0.469
2004	0.458
2005	0.447
2006	0.439
2007	0.432
2008	0.425
2009	0.411
2010	0.398
2011	0.393
2012	0.384
2013	0.371
2014	0.361
2015	0.353
2016	0.349
2017	0.345
2018	0.343
2019	0.338
2020	0.332
2021	0.326
2022	0.319
2023	0.313
2024	0.306