Year	Percent
1991	58.539
1992	55.923
1993	51.6
1994	51.65
1995	52.182
1996	54.903
1997	57.144
1998	57.664
1999	56.981
2000	57.416
2001	56.47
2002	57.676
2003	59.154
2004	61.561
2005	64.602
2006	65.278
2007	67.534
2008	63.079
2009	65.148
2010	66.228
2011	67.02
2012	68.056
2013	67.523
2014	66.839
2015	66.724
2016	66.376
2017	66.281
2018	66.421
2019	66.745
2020	67.27
2021	67.506
2022	67.718