Year	Percent
1983	11.9038
1985	11.1232
1987	12.8106
1988	12.3575
1989	11.4518
1990	10.8785
1991	9.5417
1992	7.7486
1993	7.3297
1994	8.0357
1995	7.9167
1996	7.4619
1997	6.5367
1998	5.1366
1999	4.1402
2000	2.9928
2001	2.1452
2002	2.5365
2003	3.2995
2004	4.4339
2005	4.475
2006	3.8245
2007	3.0784
2008	2.4428
2009	2.8566
2010	3.6892
2011	4.5393
2012	5.122
2013	6.211
2014	6.6392
2015	6.2918
2016	5.3703
2017	4.2087