Year	Percent
1991	83.031
1992	82.898
1993	82.728
1994	82.523
1995	82.266
1996	82.135
1997	81.956
1998	81.746
1999	81.53
2000	81.337
2001	81.16
2002	82.072
2003	82.023
2004	81.968
2005	81.885
2006	81.876
2007	82.078
2008	82.373
2009	82.943
2010	82.625
2011	82.201
2012	83.521
2013	84.817
2014	86.131
2015	86.014
2016	85.861
2017	85.935
2018	86.01
2019	86.081
2020	86.148
2021	86.212
2022	86.274