Year	Percent
1978	0.9404
1979	0.5375
1980	0.6197
1981	0.698
1982	1.3268
1983	1.8748
1984	1.6509
1985	2.1001
1986	1.9899
1987	1.3635
1988	1.1643
1989	1.1077
1990	1.2572
1991	1.1288
1992	1.0536
1993	1.017
1994	1.2291
1995	1.5072
1996	2.3745
1997	2.6275
1998	2.5192
1999	2.8882
2000	2.9569
2001	4.8054
2002	5.4423
2003	5.0322
2004	4.2995
2005	3.8712
2006	3.6707
2007	3.7599
2008	4.0829
2009	6.3467
2010	5.7051
2011	4.5016
2012	4.2622
2013	4.2265
2014	4.0439
2015	3.8657
2016	4.0262
2017	3.8446