Year	Percent
1991	81.063
1992	80.988
1993	81.264
1994	81.159
1995	81.505
1996	81.482
1997	81.227
1998	81.482
1999	81.056
2000	80.647
2001	80.976
2002	83.191
2003	82.151
2004	80.256
2005	79.96
2006	79.045
2007	78.88
2008	78.871
2009	78.602
2010	78.057
2011	76.91
2012	76.549
2013	76.159
2014	76.107
2015	76.312
2016	76.217
2017	76.234
2018	76.213
2019	76.181
2020	76.137
2021	76.094
2022	76.052