Year	Percent
1983	4.3315
1984	3.9128
1985	5.727
1986	6.0149
1987	6.5831
1988	6.7191
1989	6.6727
1990	6.7282
1991	6.3116
1992	7.4152
1993	9.6388
1994	10.7699
1995	10.4177
1996	12.282
1997	13.8778
1998	13.9276
1999	13.5839
2000	11.8348
2001	11.4475
2002	10.6176
2003	12.3932
2004	12.9303
2005	12.5534
2006	11.9186
2007	9.6779
2008	8.1181
2009	7.9386
2010	7.946
2011	6.4965
2012	6.1492
2013	6.0903
2014	5.5095
2015	5.2052
2016	4.1306
2017	3.6628