Year	Percent
1997	38.25692
1998	31.30347
1999	32.02581
2001	24.60233
2002	24.50902
2003	21.97225
2004	17.71677
2005	17.96896
2007	18.57218
2008	19.99509
2009	21.93663
2010	21.14418
2011	24.17399
2012	17.13507
2013	24.79511
2014	30.67039