Year	Percent
1976	22.03992
1977	20.40545
1978	25.01835
1979	29.39672
1980	27.6045
1981	25.26836
1982	27.32755
1983	38.39334
1984	40.7478
1985	57.73452
1986	69.69827
1987	73.36062
1988	57.96867
1989	67.68509
1990	18.24837
1991	26.95592
1992	8.00924
1993	12.93567
1994	14.41129
1995	19.11012
1996	11.59482
1997	7.70879
1998	5.1459
1999	4.88325
2000	0.43829
2001	0.19633
2002	0.24253
2003	0.18795
2004	0.15468
2005	0.12991
2006	0.12413
2007	0.14499
2008	0.09348
2009	0.09916
2010	0.0466
2011	0.02302
2012	9.68037
2013	0.54162
2014	0.46153
2015	0.53837
2016	0.7528