Year	Percent
1991	48.415
1992	46.693
1993	52.949
1994	51.832
1995	51.465
1996	49.718
1997	48.722
1998	46.526
1999	47.835
2000	46.938
2001	45.227
2002	46.567
2003	45.719
2004	44.408
2005	45.446
2006	46.261
2007	46.103
2008	47.244
2009	51.164
2010	54.412
2011	58
2012	57.713
2013	56.404
2014	56.1
2015	55.993
2016	56.242
2017	57.597
2018	57.402
2019	56.999
2020	56.465
2021	55.836
2022	55.239