Year	Percent
1980	17.35168
1981	24.94049
1982	18.20513
1983	23.40141
1984	30.33742
1985	41.67642
1986	40.71649
1987	47.93046
1988	75.68532
1989	67.63198
1990	81.36389
1991	74.79957
1992	59.65701
1993	46.01694
1994	27.49917
1995	19.83695
1996	18.20211
1997	20.17111
1998	20.79639
1999	18.52407
2000	10.56409
2001	7.06002
2002	9.79916
2003	9.80536
2004	8.85385
2005	10.78984
2006	5.52471
2007	2.62685
2008	2.34075
2009	2.11358
2010	1.79984
2011	1.47458
2012	1.36028
2013	1.67987
2014	4.38329
2015	2.00489
2016	18.82339