Year	Percent
1983	19.0348
1985	16.7254
1987	17.9527
1988	14.4651
1989	13.8501
1990	11.9456
1991	11.9759
1992	8.5494
1993	9.5473
1994	8.9882
1995	12.7272
1996	11.6068
1997	10.3009
1998	9.2702
1999	8.1503
2000	5.8564
2001	4.5308
2002	4.8418
2003	6.4889
2004	8.1146
2005	8.3822
2006	7.0629
2007	6.2452
2008	5.1868
2009	6.1106
2010	8.5938
2011	9.5421
2012	11.6417
2013	12.8592
2014	13.0766
2015	11.1737
2016	10.2513
2017	8.766