Year	Percent
1991	82.619
1992	82.288
1993	82.067
1994	81.73
1995	81.288
1996	80.151
1997	79.645
1998	79.404
1999	78.411
2000	77.521
2001	77.343
2002	76.106
2003	76.014
2004	78.71
2005	82.05
2006	80.643
2007	79.466
2008	78.045
2009	77.718
2010	75.364
2011	72.814
2012	71.241
2013	77.235
2014	76.904
2015	76.362
2016	75.759
2017	74.334
2018	73.696
2019	73.108
2020	72.443
2021	71.712
2022	71.37