Year	Percent
1991	45.62668
1992	48.22774
1993	48.94034
1994	50.38352
1995	51.20014
1996	44.78907
1997	45.54473
1998	45.7591
1999	44.74132
2000	47.71956
2001	49.36751
2002	51.23545
2003	48.84163
2004	48.43164
2005	49.6719
2006	48.0093
2007	48.54869
2008	49.03861
2009	48.74265
2010	49.64549
2011	50.48241
2012	50.86042
2013	51.96551
2014	51.4088
2015	50.84811
2016	51.20044
2017	54.16027