Year	Percent
1991	87.22
1992	86.471
1993	85.455
1994	84.904
1995	84.628
1996	83.874
1997	83.53
1998	83.183
1999	82.239
2000	81.293
2001	79.682
2002	78.235
2003	77.235
2004	75.468
2005	73.644
2006	72.004
2007	69.964
2008	68.206
2009	66.75
2010	65.087
2011	64.182
2012	63.451
2013	62.591
2014	61.325
2015	60.551
2016	60.6
2017	60.579
2018	60.45
2019	60.32
2020	60.199
2021	60.09
2022	59.986