Year	Percent
1970	12.12136
1971	12.11904
1972	12.11891
1973	12.12324
1974	12.1326
1975	12.11299
1976	12.10747
1977	12.11828
1978	12.14488
1979	12.17936
1980	12.01497
1981	12.07983
1982	12.17233
1983	12.27792
1984	12.35176
1985	11.19302
1986	12.40412
1987	12.63483
1988	12.80586
1989	12.72097
1990	13.04055
1991	12.77595
1992	12.42662
1993	9.57115
1994	7.89981
1995	6.8833
1996	7.13344
1997	7.18681
1998	6.11742
1999	6.12418
2000	6.60126
2001	6.37957
2002	5.94573
2003	5.74521
2004	5.47444
2005	4.36365
2006	3.40501
2007	3.9081
2008	3.81704
2009	3.93041
2010	3.61429
2011	3.60487
2012	3.8501
2013	3.92492
2014	3.93771
2015	3.83575
2016	3.93834
2017	3.80018
2018	3.78237
2019	3.56733
2020	2.76195
2021	0.88194
2022	0.80026