Year	Percent
1998	4.228
1999	4.16762
2000	4.06928
2001	3.79861
2002	3.20122
2003	3.37588
2004	3.00401
2005	2.70056
2006	1.42344
2007	1.07962
2008	1.48596
2009	3.40349
2010	5.18025
2011	4.16421
2012	4.37931
2013	3.182
2014	2.73116
2015	2.40727
2016	2.25057
2017	1.87131