Year	Percent
1979	5.1632
1980	5.0692
1981	4.8095
1982	6.3521
1983	9.7163
1984	8.687
1985	7.9409
1986	7.6707
1987	7.7604
1988	6.7673
1989	5.7091
1990	6.7364
1991	9.8878
1992	11.308
1993	11.5097
1994	9.9825
1995	8.7422
1996	8.7105
1997	8.5836
1998	7.9413
1999	7.0371
2000	6.456
2001	6.9786
2002	6.5314
2003	5.8884
2004	5.2812
2005	4.8791
2006	4.6676
2007	4.0404
2008	3.955
2009	5.694
2010	5.0746
2011	4.8942
2012	5.1389
2013	5.7077
2014	5.9983
2015	6.0415
2016	5.6509
2017	5.5285