Year	Percent
1998	18.9078
1999	20.9937
2000	27.2917
2001	24.6458
2002	21.5655
2003	32.7758
2004	16.5256
2005	15.4586
2006	9.9778
2007	10.4447
2008	13.8785
2009	22.357
2010	31.5787
2011	29.3671
2012	22.7007
2013	20.3583
2014	18.7139
2015	16.6471
2016	12.6252
2017	11.658