Year	Percent
1975	0.60359
1976	1.63126
1977	1.25009
1978	1.26645
1979	1.21031
1980	1.40308
1981	1.40964
1985	1.55888
1986	1.56493
1987	1.61078
1988	1.26629
1989	1.49654
1990	2.13257
1991	1.38954
1992	1.33791
1993	1.37864
1994	1.52252
1995	1.16535
1996	1.52869
1997	1.61591
1998	1.32119
1999	1.03893
2000	0.96037
2001	0.82241
2002	0.55846
2003	0.51958
2004	0.58473
2005	0.62605
2006	0.56639
2007	0.61851
2008	0.50642
2009	0.67311
2010	0.48859
2011	0.53634
2012	0.7806
2013	0.74282
2014	0.73408
2015	0.71236
2016	0.58775
2017	0.48751