Year	Percent
1974	7.6
1982	8.6
1986	13.01
1987	12.24
1990	4.31
1991	4.28
1992	3.12
1995	3.17
1996	4.35
1997	3.32
1998	3.84
1999	3.98
2001	3.96
2002	3.63
2003	4.65
2004	4.79
2005	4.066
2006	3.1282
2007	2.6307
2008	2.7741
2009	2.7398
2010	3.3728
2011	3.452
2012	3.0086
2013	3.5097
2014	4.5875
2015	3.4571
2016	4.1265
2017	3.1241