Year	Percent
1981	3.54862
1982	17.01049
1983	13.35269
1984	12.74901
1985	23.92523
1986	10.0332
1987	9.42764
1988	20.16546
1989	15.09741
1990	6.4255
1991	5.99924
1992	10.28864
1993	8.65485
1994	20.69416
1995	6.58355
1996	14.95034
1997	6.94071
1998	8.33149
1999	6.69946
2000	12.33558
2001	11.25937
2002	10.7283
2003	1.00671
2004	1.90399
2005	5.52868
2006	9.27291
2007	6.90902
2008	10.90851
2009	6.96289
2010	3.56414
2011	3.80506
2012	12.88187
2013	8.79632
2014	6.25818
2015	1.98502
2016	10.00843
2017	6.82171