Year	Percent
1976	26.06962
1977	30.30376
1978	28.4619
1979	25.77074
1980	26.17491
1981	26.29384
1982	26.95069
1983	35.17997
1984	36.01891
1985	39.44804
1986	38.59877
1987	35.88646
1988	34.55753
1989	30.19319
1990	27.21717
1991	24.51095
1992	26.99483
1993	28.29376
1994	38.06372
1995	30.8384
1996	30.85799
1997	40.56096
1998	24.92706
1999	32.48358
2000	28.38829
2001	28.36439
2002	23.44557
2003	20.52259
2004	26.3678
2005	12.47743
2006	10.84176
2007	11.43277
2008	11.28945
2009	15.10673
2010	14.99836
2011	9.20862
2012	15.32856
2013	22.6573
2014	15.21051
2015	12.85427
2016	15.3546