Year	Percent
1991	80.219
1992	81.085
1993	80.935
1994	80.446
1995	80.051
1996	80.478
1997	81.277
1998	76.97
1999	77.075
2000	76.47
2001	77.062
2002	77.633
2003	79.204
2004	79.053
2005	79.144
2006	79.168
2007	78.727
2008	77.995
2009	76.898
2010	76.12
2011	76.698
2012	77.211
2013	77.092
2014	76.926
2015	77.892
2016	78.655
2017	78.878
2018	78.854
2019	78.831
2020	78.813
2021	78.799
2022	78.786