Year	Percent
1984	2.57408
1985	2.88779
1986	4.67073
1987	3.79251
1988	6.62998
1989	6.21044
1990	6.43774
1991	6.40435
1992	6.24514
1993	5.74023
1994	5.98247
1995	5.47727
1996	6.24949
1997	7.18396
1998	7.52984
1999	6.13042
2000	4.06921
2001	3.8864
2002	3.87078
2003	3.71142
2004	2.53273
2005	2.60809
2006	2.55818
2007	2.63837
2008	2.51496
2009	3.25885
2010	2.85049
2011	2.24224
2012	2.15904
2013	2.27751
2014	3.08686
2015	3.27929
2016	3.53939
2017	2.87923