Year	Percent
1991	75.899
1992	75.28
1993	74.624
1994	73.882
1995	72.99
1996	72.453
1997	71.835
1998	71.161
1999	70.489
2000	69.902
2001	70.115
2002	70.677
2003	71.665
2004	72.296
2005	72.888
2006	74.27
2007	74.067
2008	74.408
2009	74.203
2010	75.298
2011	75.837
2012	76.087
2013	77.071
2014	77.691
2015	77.967
2016	77.857
2017	78.316
2018	78.71
2019	79.053
2020	79.343
2021	79.388
2022	79.359