Year	Percent
1983	8.5707
1984	9.0024
1985	8.69
1986	8.1914
1987	8.1591
1988	9.1309
1989	9.1304
1990	8.5642
1991	9.6006
1992	9.9139
1993	10.5093
1994	10.6932
1995	10.8743
1996	12.3142
1997	11.9314
1998	13.9784
1999	15.4853
2000	14.9693
2001	13.9801
2002	13.6668
2003	12.8979
2004	14.3894
2005	14.3401
2006	12.525
2007	12.0209
2008	10.884
2009	12.413
2010	15.5198
2011	20.6483
2012	27.1488
2013	30.857
2014	29.7635
2015	28.6908
2016	28.0575
2017	25.6334