Year	Percent
1983	6.027
1984	6.2166
1985	6.4232
1986	7.5324
1987	7.6675
1988	7.3756
1989	6.8224
1990	6.0069
1991	5.5768
1992	7.0607
1993	7.3244
1994	7.0208
1995	6.8825
1996	8.245
1997	8.0804
1998	8.0159
1999	8.4197
2000	7.2851
2001	5.4696
2002	5.8502
2003	5.3332
2004	4.6902
2005	4.749
2006	5.1862
2007	4.6618
2008	4.2437
2009	5.6836
2010	6.0473
2011	5.7742
2012	6.4588
2013	7.5046
2014	8.0299
2015	7.959
2016	8.1171
2017	7.272