Year	Percent
1997	34.05098
1998	31.62065
1999	27.03476
2000	22.31439
2001	19.38636
2002	18.0672
2003	13.52347
2004	11.57517
2006	14.28632
2007	14.70856
2008	15.60184
2009	12.37232
2010	12.51719
2011	15.81882
2012	22.0796
2013	24.17524
2014	21.6053