Year	Percent
1977	13.23435
1978	17.17791
1979	16.1805
1980	25.60314
1981	24.00394
1982	32.27806
1983	27.93388
1984	21.79691
1985	17.97375
1986	44.4735
1987	21.11024
1988	29.86191
1989	11.61057
1990	9.7106
1991	5.79749
1992	7.20683
1993	5.38417
1994	0.53631
1995	10.10265
1996	7.06712
1997	8.95316
1998	9.78871
1999	6.76953
2000	13.47289
2001	13.74981
2002	6.91257
2003	10.71805
2004	8.52858
2005	7.97715
2006	5.02152
2007	3.98009
2008	2.99988
2009	5.65697
2010	4.18412
2011	4.83441
2012	7.04787
2013	4.87252
2014	4.28736
2015	10.60814
2016	6.3927