Year	Percent
1976	6.8589
1977	7.642
1978	8.1203
1979	7.2983
1980	6.8124
1981	7.0954
1982	9.137
1983	9.9659
1984	10.1683
1985	9.6574
1986	8.8322
1987	8.4701
1988	7.7163
1989	7.4588
1990	7.5579
1991	9.0366
1992	9.2828
1993	9.9336
1994	9.0335
1995	8.3007
1996	8.4766
1997	7.6991
1998	6.9252
1999	6.3328
2000	5.7785
2001	6.0371
2002	6.2461
2003	6.3246
2004	5.8869
2005	5.6861
2006	5.2375
2007	4.7553
2008	4.7605
2009	6.102
2010	6.3933
2011	6.033
2012	5.7673
2013	5.5919
2014	5.4493
2015	5.4322
2016	5.388
2017	5.1703