Year	Percent
1997	18.13375
1998	29.75334
2002	29.99078
2003	31.71205
2004	29.40803
2005	28.10482
2006	25.36861
2007	25.6322
2008	24.61355
2009	28.30466
2010	26.76168
2011	25.75067
2013	24.491
2014	24.23162