Year	Percent
1980	3.054
1981	3.259
1982	3.232
1983	3.041
1984	3.013
1985	2.973
1986	2.783
1987	2.726
1988	2.642
1989	2.653
1990	2.681
1991	2.729
1992	2.537
1993	2.557
1994	2.606
1995	2.356
1996	2.424
1997	2.487
1998	2.547
1999	2.53
2000	2.533
2001	2.463
2002	2.393
2003	2.332
2004	2.303
2005	2.248
2006	2.23
2007	2.164
2008	2.127
2009	2.023
2010	2.02
2011	2.011
2012	2.02
2013	1.981
2014	1.968
2015	1.967
2016	1.961
2017	1.93
2018	1.901
2019	1.871
2020	1.842
2021	1.82
2022	1.804
2023	1.789
2024	1.775