Year	Percent
1983	5.0185
1984	3.7701
1985	4.3169
1986	3.9759
1987	3.7514
1988	2.931
1989	2.3906
1990	2.3955
1991	2.122
1992	2.784
1993	3.1318
1994	4.2939
1995	4.3849
1996	4.6566
1997	3.6434
1998	4.1616
1999	3.3304
2000	3.1416
2001	2.1674
2002	3.6302
2003	4.7091
2004	7.0947
2005	5.8237
2006	6.2459
2007	4.7124
2008	6.0303
2009	6.1262
2010	5.0925
2011	6.2574
2012	5.9065
2013	6.3849
2014	5.7668
2015	7.3442
2016	6.6295
2017	5.4989