Year	Percent
1990	43.13306
1991	41.69288
1992	34.69681
1993	38.11445
1994	38.16589
1995	44.14111
1996	44.51659
1997	48.28178
1998	44.74003
1999	45.57459
2000	46.40237
2001	44.48526
2002	43.60014
2003	46.19296
2004	49.35906
2005	51.74736
2006	50.20134
2007	48.98922
2008	52.81835
2009	46.126
2010	48.73197
2011	48.62687
2012	47.46207
2013	51.99241
2014	50.69819
2015	43.77256
2016	46.21389
2017	43.70869