Year	Percent
1983	4.9769
1984	5.0434
1985	5.1543
1986	5.2267
1987	5.7726
1988	4.8664
1989	4.1246
1990	3.5843
1991	4.0161
1992	4.4798
1993	5.8381
1994	6.7998
1995	6.306
1996	7.3012
1997	8.176
1998	8.2996
1999	7.5251
2000	6.7126
2001	7.0638
2002	8.147
2003	9.4359
2004	10.5323
2005	10.5621
2006	9.5185
2007	7.8457
2008	6.8652
2009	7.6364
2010	6.9072
2011	5.5924
2012	5.0982
2013	5.0884
2014	4.9546
2015	4.6774
2016	4.2196
2017	3.9003