Year	Percent
1991	41.35011
1992	44.01921
1993	44.08733
1994	42.07225
1995	41.54873
1996	42.5697
1997	44.59498
1998	44.68835
1999	44.50196
2000	45.02394
2001	43.86942
2002	41.77577
2003	41.3173
2004	41.49391
2005	42.22292
2006	43.89409
2007	43.24249
2008	42.72165
2009	44.74559
2010	42.83295
2011	43.66435
2012	46.45087
2013	45.51207
2014	45.66323
2015	46.20568
2016	45.1119
2017	45.52273