Year	Percent
1991	82.625
1992	84.07
1993	85.707
1994	86.54
1995	86.92
1996	86.772
1997	83.935
1998	83.67
1999	82.74
2000	81.383
2001	81.862
2002	82.021
2003	83.294
2004	82.869
2005	82.708
2006	81.996
2007	81.807
2008	81.865
2009	81.711
2010	81.189
2011	80.414
2012	80.004
2013	79.512
2014	79.793
2015	80.304
2016	80.416
2017	80.348
2018	80.298
2019	80.243
2020	80.185
2021	80.125
2022	80.069