Year	Percent
1991	68.377
1992	68.494
1993	68.236
1994	68.376
1995	68.147
1996	68.204
1997	68.289
1998	68.408
1999	68.214
2000	68.077
2001	67.885
2002	67.542
2003	67.177
2004	66.903
2005	66.683
2006	66.74
2007	66.746
2008	66.878
2009	66.961
2010	67.07
2011	67.207
2012	67.344
2013	67.392
2014	67.339
2015	67.33
2016	67.298
2017	67.267
2018	67.243
2019	67.212
2020	67.174
2021	67.134
2022	67.086