Year	Percent
1986	6.7109
1987	5.777
1988	4.298
1989	3.4841
1990	3.2712
1991	2.5964
1992	3.3656
1993	4.5208
1994	5.8507
1995	6.4767
1996	6.357
1997	5.8032
1998	3.801
1999	4.1762
2000	3.0381
2001	2.8894
2002	3.8115
2003	5.1623
2004	5.5744
2005	6.6532
2006	6.5331
2007	6.5952
2008	6.474
2009	8.8279
2010	9.755
2011	12.3431
2012	15.554
2013	16.0104
2014	13.484
2015	12.1559
2016	10.971
2017	8.4063