Year	Percent
1991	88.612
1992	88.385
1993	88.139
1994	87.889
1995	87.634
1996	87.368
1997	87.104
1998	86.835
1999	86.494
2000	86.17
2001	85.851
2002	85.529
2003	85.178
2004	84.398
2005	83.566
2006	84.013
2007	82.774
2008	81.549
2009	80.238
2010	78.866
2011	77.404
2012	75.86
2013	74.224
2014	72.474
2015	72.361
2016	72.241
2017	72.115
2018	71.984
2019	71.846
2020	71.705
2021	71.566
2022	71.42