Year	Percent
1998	16.89746
1999	16.40668
2000	15.88091
2001	16.57672
2002	16.98496
2003	18.45843
2004	19.65692
2005	20.01628
2006	21.10969
2007	22.49283
2008	26.63316
2009	28.67156
2010	27.46586
2011	27.23838
2012	25.86267
2014	21.61409