Year	Percent (Units)
1980	0.346
1981	0.362
1982	0.382
1983	0.396
1984	0.409
1985	0.391
1986	0.383
1987	0.389
1988	0.409
1989	0.430
1990	0.450
1991	0.482
1992	0.472
1993	0.509
1994	0.540
1995	0.572
1996	0.606
1997	0.625
1998	0.563
1999	0.577
2000	0.599
2001	0.588
2002	0.602
2003	0.612
2004	0.621
2005	0.623
2006	0.625
2007	0.631
2008	0.642
2009	0.636
2010	0.649
2011	0.658
2012	0.671
2013	0.663
2014	0.678
2015	0.669
2016	0.673
2017	0.676
2018	0.684
2019	0.695
2020	0.677
2021	0.657
2022	0.691
2023	0.695
2024	0.703
2025	0.711
2026	0.720
2027	0.726
2028	0.733
2029	0.739