Year	Percent
1980	0.63
1981	0.664
1982	0.717
1983	0.791
1984	0.837
1985	0.871
1986	0.936
1987	1.013
1988	1.085
1989	1.12
1990	1.182
1991	1.274
1992	1.215
1993	1.273
1994	1.35
1995	1.427
1996	1.48
1997	1.505
1998	1.386
1999	1.491
2000	1.549
2001	1.581
2002	1.651
2003	1.633
2004	1.628
2005	1.614
2006	1.611
2007	1.612
2008	1.611
2009	1.629
2010	1.647
2011	1.641
2012	1.627
2013	1.619
2014	1.617
2015	1.609
2016	1.604
2017	1.594
2018	1.58
2019	1.57
2020	1.559
2021	1.548
2022	1.537
2023	1.528
2024	1.517