Year	Percent
1991	79.715
1992	79.44
1993	79.556
1994	79.637
1995	80.025
1996	79.828
1997	79.712
1998	79.563
1999	78.928
2000	78.289
2001	77.65
2002	76.975
2003	76.267
2004	75.522
2005	74.735
2006	73.94
2007	73.118
2008	72.265
2009	71.382
2010	70.471
2011	69.538
2012	68.618
2013	67.676
2014	66.743
2015	65.829
2016	64.906
2017	64.782
2018	64.679
2019	64.592
2020	64.609
2021	64.628
2022	64.658