Year	Percent
1980	14.008
1981	16.82
1982	13.586
1983	9.897
1984	11.188
1985	8.645
1986	6.825
1987	7.314
1988	8.128
1989	9.268
1990	8.316
1991	6.077
1992	3.932
1993	3.426
1994	5.071
1995	6.098
1996	5.591
1997	5.844
1998	5.538
1999	5.529
2000	6.649
2001	3.728
2002	1.882
2003	1.23
2004	1.792
2005	3.765
2006	5.273
2007	5.252
2008	3.045
2009	1.121
2010	0.518
2011	0.507
2012	0.687
2013	0.409
2014	0.329
2015	0.484
2016	1.056
2017	1.476
2018	2.486
2019	3.222
2020	3.81