Year	Percent
1976	3.75991
1977	5.39294
1978	13.80044
1979	11.53096
1980	18.22337
1981	18.85163
1982	24.94173
1983	29.49418
1984	24.5935
1985	38.992
1986	34.43637
1987	39.18779
1988	31.92391
1989	32.95285
1990	32.89362
1991	40.44552
1992	40.12629
1993	26.81446
1994	18.9424
1995	17.43155
1996	18.84909
1997	12.64047
1998	18.97954
1999	17.88183
2000	11.93189
2001	7.82439
2002	5.32295
2003	3.9198
2004	4.47004
2005	4.36326
2006	2.531
2007	1.7255
2008	1.27277
2009	3.06974
2010	2.91454
2011	1.87088
2012	1.79753
2013	1.79714
2014	2.74031
2015	3.59072
2016	5.43383