Year	Percent
1980	0.347
1981	0.365
1982	0.385
1983	0.399
1984	0.412
1985	0.394
1986	0.385
1987	0.391
1988	0.411
1989	0.433
1990	0.453
1991	0.485
1992	0.474
1993	0.511
1994	0.542
1995	0.574
1996	0.609
1997	0.627
1998	0.566
1999	0.581
2000	0.602
2001	0.591
2002	0.605
2003	0.615
2004	0.624
2005	0.625
2006	0.627
2007	0.632
2008	0.644
2009	0.636
2010	0.65
2011	0.657
2012	0.672
2013	0.681
2014	0.697
2015	0.709
2016	0.716
2017	0.731
2018	0.739
2019	0.749
2020	0.758
2021	0.768
2022	0.777
2023	0.787
2024	0.796