Year	Percent
1979	1.8026
1980	1.4611
1981	1.4109
1982	1.2692
1983	1.8962
1984	1.5602
1985	1.6153
1986	1.5204
1987	1.2603
1988	1.4064
1989	1.6642
1990	1.5042
1991	2.0656
1992	2.2899
1993	2.2995
1994	1.848
1995	1.5692
1996	1.8253
1997	1.6595
1998	1.1261
1999	0.9801
2000	1.155
2001	1.4876
2002	1.0339
2003	0.8703
2004	0.9682
2005	0.81
2006	1.3749
2007	1.2053
2008	0.9182
2009	1.3959
2010	1.6929
2011	1.1635
2012	1.8655
2013	1.6905
2014	2.5661
2015	1.6017
2016	1.7731
2017	1.593