Year	Percent
1997	9.03902
1998	13.49094
1999	12.57823
2000	15.23753
2001	16.58072
2002	23.6717
2003	24.0227
2004	28.07295
2005	21.73188
2006	38.34963
2007	59.98131
2008	21.2258
2009	24.16354
2010	19.63683
2011	12.33332
2012	13.96863
2013	14.81501
2014	15.06737
2015	14.01126
2016	11.77051
2017	12.95547