Year	Percent
1983	9.7528
1984	10.0099
1985	10.989
1986	10.8945
1987	10.4239
1988	8.6314
1989	7.1441
1990	6.6229
1991	7.3983
1992	7.4185
1993	7.7418
1994	7.3851
1995	6.9137
1996	6.3169
1997	5.7958
1998	5.3522
1999	5.1502
2000	4.8598
2001	4.1127
2002	4.3614
2003	4.0637
2004	4.1902
2005	4.2926
2006	4.9455
2007	4.9606
2008	5.086
2009	6.4205
2010	6.875
2011	7.3406
2012	7.3862
2013	7.0386
2014	5.8213
2015	5.1251
2016	4.6838
2017	4.2199