Year	Percent
1986	2.1904
1987	1.8554
1988	1.4533
1989	1.609
1990	1.3845
1991	1.7462
1992	0.8977
1993	2.0283
1994	2.0886
1995	2.6126
1996	3.59
1997	3.3612
1998	2.9133
1999	2.3197
2000	2.5767
2001	2.579
2002	3.6859
2003	3.4665
2004	4.7997
2005	5.1955
2006	5.1602
2007	5.8036
2008	5.7622
2009	6.9215
2010	7.6841
2011	9.5474
2012	10.6957
2013	12.55
2014	11.4444
2015	10.723
2016	9.0482
2017	8.0602