Year	Percent
1991	78.3
1992	78.07
1993	77.879
1994	77.403
1995	77.052
1996	76.549
1997	76
1998	75.452
1999	74.821
2000	74.122
2001	73.452
2002	72.696
2003	71.953
2004	71.186
2005	70.087
2006	69.367
2007	68.655
2008	67.931
2009	67.226
2010	66.411
2011	65.883
2012	65.367
2013	64.762
2014	64.21
2015	63.586
2016	62.912
2017	62.699
2018	62.438
2019	62.136
2020	61.804
2021	61.46
2022	61.076