Year	Percent
1977	11.87659
1978	33.00333
1979	15.83526
1980	6.21229
1981	5.67644
1982	6.78583
1983	6.65332
1984	8.54701
1985	7.32724
1986	8.30804
1987	7.64587
1988	0.62002
1989	0.28441
1990	6.18785
1991	5.17392
1992	12.9375
1993	3.6277
1994	4.45865
1995	3.41939
1996	10.19447
1997	15.93174
1998	7.37922
1999	8.36387
2000	9.47642
2001	12.24764
2002	19.54047
2003	11.21208
2004	14.39505
2005	17.56327
2006	21.80072
2007	5.11938
2008	8.9565
2009	5.94061
2010	6.20445
2011	5.45898
2012	6.14257
2013	6.23436
2014	7.39977
2015	8.87699
2016	21.83317