Year	Percent
1976	4.0365
1977	5.0798
1978	5.6176
1979	4.6819
1980	4.4441
1981	4.6257
1982	7.3018
1983	8.563
1984	8.4226
1985	8.6913
1986	7.5034
1987	6.8125
1988	6.4439
1989	6.5168
1990	6.3093
1991	8.4416
1992	9.7745
1993	10.2092
1994	9.6906
1995	8.5163
1996	7.9632
1997	7.5775
1998	6.9565
1999	6.3643
2000	5.454
2001	5.9505
2002	6.5905
2003	6.8292
2004	6.1052
2005	5.3966
2006	5.3279
2007	5.2105
2008	5.7614
2009	8.0815
2010	7.4239
2011	7.1859
2012	6.6129
2013	6.8328
2014	6.7467
2015	6.6214
2016	6.9816
2017	6.261