Year	Percent
1986	2.0166
1987	1.8114
1988	1.5008
1989	1.781
1992	5.4237
1993	2.9235
1994	3.6215
1995	2.1722
1996	2.3751
1997	2.4117
2000	4.3741
2001	3.5327
2003	3.2552
2005	3.5603
2006	1.982
2007	2.1774
2008	4.3532
2009	2.4717
2010	1.298
2011	2.6478
2012	4.0527
2013	6.2469
2014	6.2706
2015	4.0567
2016	5.8306
2017	4.2416