Year	Percent
1970	6.29927
1971	6.40296
1972	6.68667
1973	6.50773
1974	6.49009
1975	5.7093
1976	5.7678
1977	5.5259
1978	4.20352
1979	3.63634
1980	3.4837
1981	3.54038
1982	3.73087
1983	4.20641
1984	4.31158
1985	4.1826
1986	4.09893
1987	4.00949
1988	3.5764
1989	3.42771
1990	3.15177
1991	2.98488
1992	2.76373
1993	2.74297
1994	2.56111
1995	2.25884
1996	2.25869
1997	2.22899
1998	2.35636
1999	2.18596
2000	1.87205
2001	2.19665
2002	2.1332
2003	1.96163
2004	1.89542
2005	1.84023
2006	1.86947
2007	1.83022
2008	1.0601
2009	1.43868
2010	1.26561
2011	0.99191
2012	1.0556
2013	1.06986
2014	1.00416
2015	0.92288
2016	0.92643
2017	0.66701
2018	0.66535
2019	0.46526
2020	0.76375
2021	0.88873
2022	0.9386