Year	Percent
1983	7.3591
1984	8.3783
1985	9.1528
1986	9.3832
1987	10.8766
1988	10.6157
1989	11.0144
1990	10.5515
1991	10.1045
1992	11.3321
1993	11.8038
1994	13.0109
1995	12.5432
1996	13.0685
1997	13.0139
1998	12.886
1999	12.7238
2000	11.4019
2001	9.7103
2002	8.9783
2003	8.5596
2004	9.0361
2005	8.4018
2006	8.028
2007	7.2205
2008	6.6653
2009	7.7252
2010	7.9246
2011	8.1012
2012	8.4027
2013	8.7267
2014	9.1751
2015	9.0102
2016	8.9843
2017	8.8172