Year	Percent
1991	69.227
1992	68.759
1993	68.118
1994	68.014
1995	68.348
1996	68.111
1997	68.483
1998	68.777
1999	68.869
2000	69.162
2001	69.366
2002	69.575
2003	69.686
2004	69.794
2005	69.724
2006	69.817
2007	69.684
2008	69.625
2009	69.519
2010	69.35
2011	68.741
2012	68.49
2013	68.348
2014	68.067
2015	67.895
2016	67.88
2017	67.828
2018	67.785
2019	67.747
2020	67.716
2021	67.686
2022	67.664