Year	Percent
1999	3.1
2000	2.6781
2001	2.4048
2002	2.7385
2003	2.4725
2004	2.7605
2005	3.3567
2006	3.2843
2007	4.0634
2008	4.5925
2009	3.5318
2010	3.1133
2011	2.6873
2012	2.3001
2013	2.4526
2014	2.2201
2015	2.5281
2016	2.8032
2017	2.542