Year	Percent
1991	56.58
1992	56.557
1993	57.162
1994	56.726
1995	56.797
1996	55.444
1997	55.11
1998	53.69
1999	53.37
2000	52.57
2001	50.587
2002	50.338
2003	48.576
2004	48.592
2005	51.169
2006	52.23
2007	54.865
2008	57.115
2009	58.794
2010	60.799
2011	62.733
2012	65.413
2013	66.314
2014	67.119
2015	62.513
2016	61.921
2017	58.245
2018	57.467
2019	56.794
2020	56.069
2021	55.356
2022	54.643