Year	Percent
1991	68.031
1992	69.282
1993	70.566
1994	68.735
1995	65.824
1996	66.628
1997	67.739
1998	68.323
1999	68.256
2000	65.973
2001	64.551
2002	61.939
2003	60.31
2004	60.557
2005	59.766
2006	60.113
2007	59.881
2008	59.078
2009	56.146
2010	56.448
2011	55.839
2012	56.027
2013	55.144
2014	54.14
2015	54.137
2016	54.131
2017	54.49
2018	54.376
2019	54.286
2020	54.112
2021	53.935
2022	53.758