Year	Percent
1976	1.55179
1977	1.43813
1978	1.50561
1979	1.85121
1980	3.15854
1981	3.31151
1982	4.35774
1983	4.01306
1984	3.97914
1985	4.3141
1986	4.83999
1987	4.18131
1988	3.36976
1989	4.30771
1990	3.9272
1991	3.26116
1992	2.95028
1993	2.71574
1994	3.10786
1995	3.69265
1996	3.03996
1997	2.82827
1998	3.36968
1999	4.33479
2000	4.03597
2001	3.31129
2002	2.97827
2003	2.82345
2004	2.54306
2005	2.45697
2006	2.46525
2007	2.18796
2008	1.4636
2009	2.54289
2010	2.95142
2011	2.08374
2012	1.9879
2013	1.89307
2014	1.89188
2015	1.8853
2016	1.98859
2017	2.23078