Year	Percent
1991	84.786
1992	85.103
1993	85.237
1994	85.154
1995	85.149
1996	84.555
1997	83.986
1998	83.41
1999	82.816
2000	82.278
2001	81.469
2002	80.818
2003	80.243
2004	79.74
2005	79.397
2006	79.637
2007	79.944
2008	80.407
2009	80.797
2010	81.164
2011	81.477
2012	81.75
2013	82.008
2014	82.186
2015	82.264
2016	82.182
2017	82.209
2018	82.218
2019	82.21
2020	82.199
2021	82.178
2022	82.155