Year	Percent
1983	6.6582
1985	4.5317
1987	5.4323
1988	4.8712
1989	3.7282
1990	2.7849
1991	4.8358
1992	2.1488
1993	2.9023
1994	2.5991
1995	3.6475
1996	3.5169
1997	3.1703
1998	1.7535
1999	2.1311
2000	1.7274
2001	1.7181
2002	2.3133
2003	2.1951
2004	3.914
2005	4.3577
2006	4.0613
2007	3.8543
2008	3.3643
2009	3.248
2010	4.2384
2011	4.5277
2012	5.3168
2013	7.2155
2014	8.1077
2015	8.4186
2016	6.951
2017	5.3113