Year	Percent
1996	16.703
1997	14.0773
1998	16.9915
1999	17.1811
2000	14.7599
2001	15.0256
2002	13.4895
2003	13.0804
2004	11.2108
2005	14.5484
2006	11.6429
2007	9.3639
2008	9.8565
2009	13.7675
2010	15.2169
2011	15.0055
2012	20.2754
2013	20.092
2014	19.3857
2015	17.6518
2016	15.629
2017	9.9384