Year	Percent
1991	69.642
1992	69.47
1993	69.206
1994	69.074
1995	68.808
1996	68.881
1997	68.772
1998	68.68
1999	68.603
2000	68.469
2001	68.449
2002	68.241
2003	68.217
2004	68.269
2005	68.311
2006	68.488
2007	68.673
2008	68.893
2009	69.052
2010	69.269
2011	69.448
2012	69.669
2013	69.857
2014	69.969
2015	70.052
2016	70.173
2017	70.267
2018	70.337
2019	70.397
2020	70.45
2021	70.491
2022	70.531