Year	Percent
1981	0.71517
1982	1.71242
1983	2.98918
1984	4.11885
1985	10.22766
1986	15.6021
1987	17.195
1988	22.16684
1989	26.82621
1990	19.44096
1991	6.57143
1992	8.75082
1993	6.57615
1994	13.03599
1995	16.46139
1996	19.77635
1997	20.1535
1998	21.92956
1999	20.70488
2000	17.50619
2001	17.50332
2002	16.67123
2003	9.99476
2004	15.89856
2005	25.27218
2006	17.02579
2007	22.55571
2008	17.70986
2009	19.97406
2010	16.11987
2011	12.75366
2012	13.88407
2013	16.70373
2014	13.98577
2015	28.57811
2016	23.56863