Year	Percent
1991	60.633
1992	58.292
1993	54.914
1994	53.852
1995	54.439
1996	54.175
1997	53.007
1998	53.469
1999	54.788
2000	55.426
2001	56.366
2002	56.498
2003	56.139
2004	55.424
2005	55.08
2006	54.932
2007	55.845
2008	55.891
2009	54.614
2010	53.892
2011	54.835
2012	55.083
2013	55.444
2014	55.745
2015	56.225
2016	56.67
2017	56.843
2018	57.157
2019	57.237
2020	57.183
2021	57.099
2022	57.009