Year	Percent
1980	0.412
1981	0.427
1982	0.425
1983	0.375
1984	0.373
1985	0.368
1986	0.398
1987	0.413
1988	0.358
1989	0.299
1990	0.273
1991	0.272
1992	0.243
1993	0.251
1994	0.274
1995	0.284
1996	0.281
1997	0.287
1998	0.279
1999	0.274
2000	0.268
2001	0.263
2002	0.27
2003	0.27
2004	0.269
2005	0.273
2006	0.279
2007	0.287
2008	0.305
2009	0.309
2010	0.318
2011	0.325
2012	0.334
2013	0.342
2014	0.339
2015	0.338
2016	0.341
2017	0.337
2018	0.338
2019	0.341
2020	0.342
2021	0.343
2022	0.344
2023	0.345
2024	0.346