Year	Percent
1976	59.90253
1977	38.80261
1978	41.9596
1979	14.56654
1980	20.10612
1981	17.15896
1982	14.09303
1983	9.24633
1984	6.1485
1985	12.54
1986	22.07007
1987	26.54234
1988	39.05229
1989	43.63863
1990	48.88269
1991	32.77037
1992	29.25631
1993	19.91565
1994	17.37665
1995	14.73929
1996	20.74398
1997	13.20063
1998	13.22047
1999	17.11693
2000	19.51082
2001	15.51862
2002	13.47883
2003	7.97604
2004	5.00239
2005	6.98269
2006	10.79941
2007	10.09973
2008	13.03437
2009	16.56076
2010	16.72918
2011	18.61138
2012	24.16147
2013	32.2659
2014	37.8592
2015	32.85503
2016	28.0234