Year	Percent
1983	0.9
1984	1.52
1985	0.68
1986	0.54
1989	0.64
1990	0.57
1991	1.04
1992	1.23
1999	0.99
2000	1.37
2004	1.53
2006	1.37
2008	2.72
2009	3
2010	2.29
2011	2.76
2012	2.14
2013	4.69
2014	4.28
2015	4.73
2016	4.99
2017	3.26
2018	3.58
2019	4.13
2020	4.14