Year	Percent
1980	2.20454
1981	2.20122
1982	2.04022
1983	1.98509
1984	1.90673
1985	4.29928
1986	4.44571
1987	3.91403
1988	4.20547
1989	4.7973
1990	4.54742
1991	4.77333
1992	4.24768
1993	2.74061
1994	3.11473
1995	2.61345
1996	2.36907
1997	3.01765
1998	3.00417
1999	2.64026
2000	2.49891
2001	2.42075
2002	2.2873
2003	2.08849
2004	2.00766
2005	1.98194
2006	1.82257
2007	1.52016
2008	1.44122
2009	1.32907
2010	1.24181
2011	1.2839
2012	1.225
2013	1.28037
2014	1.34914
2015	1.45366
2016	1.41016
2017	1.97167