Year	Percent
1991	80.879
1992	80.814
1993	80.781
1994	80.706
1995	80.592
1996	80.47
1997	79.609
1998	80.016
1999	79.967
2000	79.939
2001	79.497
2002	79.958
2003	79.792
2004	79.99
2005	79.728
2006	79.475
2007	79.208
2008	79.289
2009	79.155
2010	79.453
2011	80.35
2012	81.002
2013	81.347
2014	81.889
2015	82.028
2016	81.617
2017	81.645
2018	81.523
2019	81.345
2020	81.119
2021	80.835
2022	80.498