Year	Percent
1997	18.12812
1998	17.20986
1999	21.01852
2001	18.23332
2002	19.45395
2003	19.05644
2004	18.71725
2005	19.14064
2007	19.04615
2008	25.0567
2009	25.82164
2010	23.95584
2011	22.28203
2012	22.03247
2013	23.22409
2014	19.70377