Year	Percent
1981	2.15
1982	2.27
1987	2.4
1989	1.94
2003	2.81
2004	2.97
2006	1.9
2010	3.5
2011	4.13
2012	2.76
2013	3.02
2014	2.72
2015	2.51
2016	2.58
2017	2.46
2018	2.28
2019	2.19