Year	Percent
1983	6.2652
1984	6.4321
1985	6.1274
1986	6.2091
1987	5.5628
1988	7.022
1989	8.6987
1990	7.5049
1991	9.5791
1992	10.2622
1993	9.7702
1994	6.7058
1995	9.785
1996	6.3457
1997	6.0135
1998	6.3771
1999	5.6323
2000	4.179
2001	3.9514
2002	4.1938
2003	3.7792
2004	5.8093
2005	5.8042
2006	4.306
2007	3.9504
2008	2.8367
2009	3.3608
2010	3.9505
2011	4.724
2012	5.2883
2013	5.0625
2014	4.5132
2015	4.7979
2016	4.104
2017	3.5912