Year	Percent
1970	5.10106
1971	5.07498
1972	4.58719
1973	4.44554
1974	4.39357
1975	4.11582
1976	4.40396
1977	4.43458
1978	4.22901
1979	3.7801
1980	3.62606
1981	3.61932
1982	3.41878
1983	2.95959
1984	3.07096
1985	2.85952
1986	3.12865
1987	3.19654
1988	3.0859
1989	2.90516
1990	2.98402
1991	2.91069
1992	2.62774
1993	2.60942
1994	2.60365
1995	2.58956
1996	2.22714
1997	2.06179
1998	2.26325
1999	2.05059
2000	1.78414
2001	1.54477
2002	1.47384
2003	1.25652
2004	1.33559
2005	1.35951
2006	1.36556
2007	1.20029
2008	1.08255
2009	1.23609
2010	1.52478
2011	1.30484
2012	1.07728
2013	1.25304
2014	1.38343
2015	1.48183
2016	2.0339
2017	1.91878
2018	1.8112
2019	1.78246
2020	1.84393
2021	1.65081
2022	1.54949