Year	Percent
1991	80.027
1992	80.05
1993	80.063
1994	80.442
1995	79.579
1996	79.925
1997	79.162
1998	78.913
1999	79.185
2000	79.814
2001	79.274
2002	79.312
2003	79.471
2004	78.76
2005	78.776
2006	78.538
2007	77.63
2008	77.571
2009	77.311
2010	78.003
2011	78.159
2012	78.058
2013	78.036
2014	77.662
2015	77.582
2016	77.799
2017	78.431
2018	78.629
2019	78.671
2020	78.82
2021	78.761
2022	78.693