Year	Percent
1991	61.27044
1992	61.03388
1993	60.84
1994	60.57818
1995	60.3519
1996	60.00785
1997	59.6574
1998	59.36199
1999	59.06301
2000	58.45726
2001	57.64263
2002	56.97005
2003	56.18943
2004	55.47208
2005	54.74097
2006	53.85232
2007	53.02859
2008	52.06218
2009	51.41382
2010	50.84491
2011	49.94884
2012	49.01527
2013	48.21138
2014	47.45619
2015	46.68599
2016	45.8338
2017	45.43496
2018	44.91819
2019	44.29523