Year	Percent
1991	78.457
1992	78.134
1993	78.008
1994	77.417
1995	77.361
1996	77.169
1997	76.977
1998	76.956
1999	76.923
2000	76.714
2001	76.505
2002	83.465
2003	83.43
2004	83.357
2005	83.151
2006	82.98
2007	82.85
2008	82.548
2009	81.924
2010	81.622
2011	81.402
2012	81.217
2013	80.856
2014	80.399
2015	80.209
2016	80.181
2017	80.128
2018	80.065
2019	80.01
2020	79.955
2021	79.906
2022	79.86