Year	Percent
1983	9.2844
1984	9.0731
1985	9.6914
1986	9.7329
1987	9.6605
1988	7.524
1989	6.2537
1990	5.8188
1991	7.7732
1992	9.9955
1993	10.3982
1994	9.7576
1995	8.5122
1996	8.029
1997	6.6322
1998	5.5192
1999	5.4374
2000	4.8489
2001	4.0695
2002	4.4013
2003	4.1643
2004	3.8004
2005	3.5934
2006	4.0829
2007	3.733
2008	4.3331
2009	6.5059
2010	6.6288
2011	6.3263
2012	5.8948
2013	5.7697
2014	4.5244
2015	3.9224
2016	3.4399
2017	3.0237