Year	Percent
1991	68.767
1992	68.444
1993	68.368
1994	67.538
1995	67.627
1996	67.314
1997	67.025
1998	67.003
1999	66.89
2000	66.528
2001	66.284
2002	75.119
2003	75.019
2004	74.857
2005	74.535
2006	74.242
2007	73.981
2008	73.43
2009	72.49
2010	71.942
2011	71.542
2012	71.157
2013	70.59
2014	69.877
2015	69.588
2016	69.547
2017	69.491
2018	69.423
2019	69.368
2020	69.313
2021	69.263
2022	69.214