Year	Percent
1991	75.074
1992	74.413
1993	74.051
1994	73.619
1995	72.667
1996	73.425
1997	75.697
1998	75.176
1999	77.47
2000	78.558
2001	80.652
2002	75.1
2003	77.663
2004	78.43
2005	77.904
2006	76.753
2007	77.778
2008	77.428
2009	76.244
2010	76.852
2011	78.233
2012	79.593
2013	79.613
2014	80.971
2015	80.886
2016	80.804
2017	80.736
2018	80.643
2019	80.526
2020	80.396
2021	80.267
2022	80.126