Year	Percent
1976	2.40212
1977	2.8723
1978	3.82006
1979	5.08736
1980	7.64177
1981	15.45426
1982	17.27499
1983	23.16818
1984	25.205
1985	23.66576
1986	14.42069
1987	10.40616
1988	14.14924
1989	9.69497
1990	8.50303
1991	8.99927
1992	8.99452
1993	6.33747
1994	7.25846
1995	8.7308
1996	6.37904
1997	7.83744
1998	8.13527
1999	6.12672
2000	16.9801
2001	5.81343
2002	7.4692
2003	5.86946
2004	5.85381
2005	5.83326
2006	5.8813
2007	2.95789
2008	2.97898
2009	3.43591
2010	1.52902
2011	49.25336
2012	38.97503
2013	27.60108
2014	26.8115
2015	28.94664
2016	18.20447