Year	Percent
1976	4.6055
1977	5.4339
1978	5.6028
1979	4.8663
1980	5.1636
1981	4.4678
1982	6.6247
1983	8.1402
1984	7.5667
1985	7.8094
1986	7.3526
1987	7.6656
1988	6.1154
1989	6.0657
1990	5.7066
1991	7.9459
1992	8.4713
1993	9.5464
1994	8.396
1995	8.0286
1996	7.5617
1997	7.6426
1998	6.7202
1999	5.325
2000	5.5077
2001	5.6383
2002	5.798
2003	5.5271
2004	5.674
2005	5.3439
2006	5.0987
2007	4.8791
2008	4.8943
2009	5.6527
2010	5.6112
2011	5.9799
2012	5.7297
2013	5.755
2014	5.4652
2015	5.436
2016	5.6333
2017	5.2179