Year	Percent
1991	68.527
1992	66.47
1993	64.433
1994	60.761
1995	60.243
1996	59.772
1997	59.474
1998	59.259
1999	59.115
2000	58.749
2001	58.463
2002	56.822
2003	55.183
2004	56.642
2005	58.102
2006	60.619
2007	60.626
2008	60.637
2009	61.128
2010	57.368
2011	61.562
2012	64.73
2013	66.91
2014	67.159
2015	67.46
2016	67.342
2017	67.277
2018	67.194
2019	67.166
2020	67.122
2021	67.046
2022	66.958