Year	Percent
1991	80.697
1992	81.741
1993	81.699
1994	82.326
1995	82.275
1996	80.998
1997	82.891
1998	82.941
1999	82.503
2000	80.214
2001	77.489
2002	76.994
2003	77.876
2004	77.84
2005	77.234
2006	76.908
2007	76.611
2008	76.008
2009	74.374
2010	73.739
2011	73.709
2012	73.626
2013	74.295
2014	76.929
2015	76.885
2016	76.522
2017	77.035
2018	77.119
2019	77.132
2020	76.99
2021	76.768
2022	76.566