Year	Percent
1991	50.84207
1992	49.83401
1993	59.92031
1994	60.82036
1995	61.77503
1996	52.7405
1997	48.46976
1998	56.28363
1999	45.27545
2000	46.83991
2001	45.14554
2002	53.79832
2003	55.03843
2004	54.41822
2005	58.20276
2006	58.72841
2007	56.67559
2008	54.00946
2009	51.54015
2010	55.09824
2011	52.53559
2012	49.92148
2013	49.56396
2014	45.18907
2015	42.28568
2016	41.74853
2017	41.79754