Year	Percent
1991	80.622
1992	81.401
1993	80.077
1994	79.87
1995	78.702
1996	78.619
1997	78.682
1998	78.434
1999	77.976
2000	76.759
2001	77.396
2002	77.232
2003	76.876
2004	77.391
2005	78.519
2006	79.452
2007	79.466
2008	79.038
2009	79.159
2010	79.26
2011	79.002
2012	79.032
2013	79.036
2014	78.861
2015	78.767
2016	78.628
2017	78.561
2018	78.497
2019	78.4
2020	78.31
2021	78.211
2022	78.09