Year	Percent
1996	16.5337
1997	19.0653
1998	18.2449
1999	19.8334
2000	18.467
2001	16.648
2002	16.6773
2003	18.3804
2004	17.6619
2005	17.7601
2006	16.8487
2007	11.1913
2008	11.2828
2009	13.3618
2010	13.8254
2011	16.7622
2012	21.0324
2013	23.6687
2014	21.2551
2015	14.5671
2016	14.7248
2017	13.0062