Year	Percent
1980	0.464
1981	0.463
1982	0.463
1983	0.469
1984	0.477
1985	0.486
1986	0.488
1987	0.478
1988	0.456
1989	0.445
1990	0.436
1991	0.439
1992	0.408
1993	0.412
1994	0.42
1995	0.422
1996	0.427
1997	0.432
1998	0.432
1999	0.426
2000	0.419
2001	0.418
2002	0.412
2003	0.399
2004	0.394
2005	0.386
2006	0.375
2007	0.367
2008	0.358
2009	0.353
2010	0.338
2011	0.328
2012	0.326
2013	0.319
2014	0.314
2015	0.31
2016	0.304
2017	0.299
2018	0.293
2019	0.289
2020	0.285
2021	0.28
2022	0.275
2023	0.27
2024	0.264