Year	Percent
1997	44.90075
2001	33.82001
2002	32.19494
2003	19.83271
2004	19.30494
2005	16.85529
2006	15.75457
2007	15.45993
2008	15.32217
2009	16.05349
2010	16.74015
2011	18.28225
2012	17.81013
2013	18.61909
2014	20.07446