Year	Percent
1983	6.847
1984	7.7623
1985	8.0295
1986	8.0655
1987	8.0558
1988	8.1016
1989	7.67
1990	6.2516
1991	6.4489
1992	8.4176
1993	9.4349
1994	10.3054
1995	9.4249
1996	9.0867
1997	9.8921
1998	9.7234
1999	8.6768
2000	7.6169
2001	7.3739
2002	7.9306
2003	9.0515
2004	9.7887
2005	10.1996
2006	9.481
2007	8.1372
2008	7.1552
2009	6.8922
2010	6.1209
2011	5.1777
2012	4.879
2013	4.6178
2014	4.3788
2015	4.0321
2016	3.5418
2017	3.1115