Year	Percent
1991	71.59
1992	71.227
1993	70.796
1994	70.332
1995	69.87
1996	69.445
1997	69.161
1998	68.896
1999	68.623
2000	67.999
2001	67.347
2002	66.641
2003	65.926
2004	65.203
2005	64.474
2006	64.476
2007	64.602
2008	64.853
2009	64.439
2010	64.446
2011	64.409
2012	64.246
2013	63.97
2014	63.662
2015	63.358
2016	63.034
2017	63.076
2018	63.11
2019	63.14
2020	63.163
2021	63.185
2022	63.2