Year	Percent
1991	68.145
1992	68.061
1993	67.756
1994	67.683
1995	66.818
1996	67.295
1997	67.4
1998	66.955
1999	66.755
2000	66.766
2001	66.152
2002	66.172
2003	65.697
2004	65.284
2005	64.966
2006	65.251
2007	64.792
2008	65.106
2009	64.655
2010	63.811
2011	63.836
2012	63.617
2013	63.008
2014	62.572
2015	62.3
2016	62.082
2017	61.974
2018	61.837
2019	61.696
2020	61.559
2021	61.423
2022	61.285